feat(updater): in-app update on desktop, releases link on Android

Anyone who installed an AppImage or ran the Windows installer was frozen
on that version forever. Nothing in the app ever mentioned a new release
existed, and the release notes were the only announcement.

Desktop now checks a signed manifest, shows the version and its notes in
Settings, and installs and relaunches on request. The signature check is
the whole point: it is what stops a substituted download from being
installed by the app itself. Windows binaries stay unsigned for
SmartScreen purposes -- that is a code-signing certificate, a separate
problem -- but the update payload is verified against our own key.

Android is deliberately not wired to the updater. An app may not replace
its own APK; that is the package installer's job, and the plugin has no
Android implementation. It gets a link to the releases page instead of a
button that would throw.

The plugins are gated with a target-triple cfg rather than
cfg(desktop). Cargo only evaluates target cfgs in a [target.'cfg(..)']
table, so cfg(desktop) matches nothing, silently drops the dependency,
and fails much later with "Permission updater:default not found" -- which
is exactly what the first attempt here did.

Where the manifest lives took some finding. This Gitea serves
/releases/download/<tag>/<asset> but 404s on
/releases/latest/download/<asset> (verified against a real asset), so
there is no stable latest-release URL. The gitea-pages branch is
force-pushed wholesale by publish-docs.yml, so it cannot host the file
either. latest.json therefore gets its own orphan branch, read over the
raw-file URL, and is published from a scratch repo in RUNNER_TEMP rather
than by switching branches in the checkout -- doing that would have left
the following steps standing on a one-commit history, and the next step
but one runs release:notes against the real commit range.

Also fixed, all of it release-integrity:

  - "appimage" is in bundle.targets. The release notes have advertised an
    AppImage for months; tauri.conf.json never built one, the artifact
    step globbed for *.AppImage, found nothing, and said nothing. The
    step now fails instead.
  - The .AppImage.tar.gz/.sig pair and the NSIS .sig are collected. A
    manifest referencing a signature that was never uploaded fails only
    on the user's machine, so the manifest step also refuses to write an
    entry with an empty signature.
  - Release notes are generated by release:notes from the traceability
    graph, which is what CLAUDE.md has asked for all along, instead of a
    fixed heredoc that said "see CHANGELOG.md for detailed changes" and
    linked "GitHub Issues" on a Gitea-hosted project.
  - The notes tell users how to verify a download with SHA256SUMS.

Requirements UR-077 / DR-217, tests UT-208 (12 cases over the version
comparison and the platform decision, including that a pre-release does
not offer itself as an upgrade to the matching release).

Verified: 1070 frontend tests, cargo check for both the host and
aarch64-linux-android (confirming the plugins are absent there), clippy
-D warnings, svelte-check 0 errors.

docs/requirements.md

@@ -86,6 +86,7 @@ For a narrative overview of the system design, see
 | UR-072 | Each page opens where a page should open. Moving to a new screen starts at the top of it, and going Back returns the viewer to the place they left — their position in a long library grid or home screen, not the top of it. A page never inherits the scroll position of the page before it | Medium | Done |
 | UR-075 | Artwork is shown at the shape it was made in. Where a screen presents a set of things side by side — the libraries on the library page and on home — they are laid out as a mosaic: rows of a common height in which each tile is as wide as its own picture, rather than a grid that crops every cover to one box. Favourites are reachable per category from that same mosaic, beside the library they belong to, not only as one undifferentiated list | Medium | Done |
 | UR-076 | Music browsing shows only what the listener considers music. A Jellyfin server commonly keeps podcasts, audiobooks, sound effects or sample packs in their own folders inside a music library; those folders can be **excluded by choice**, once, and every music surface — library grids, artist and album listings, genre rows, search and the home screen — then agrees on what is in scope. The choice is by folder, not by a name the app happens to recognise, so a folder called anything at all can be excluded and an item is never dropped because its title matched a word | Medium | Done |
+| UR-077 | The app can update itself, or tell the user how. Somebody who installed an AppImage or ran the Windows installer had no upgrade path at all: nothing in the app ever mentioned that a newer version existed, and the release notes were the only announcement. On Linux and Windows the app checks a signed manifest, offers the new version with its notes, and installs and relaunches on request — the signature check is the point, since it is what stops a substituted download from being installed by the app itself. Android cannot do this (an app may not overwrite its own APK; that is the package installer's job) and is given the honest alternative, a link to the releases page, rather than a button that would throw | Medium | Done |
 | UR-074 | Video streaming can be held to a **bandwidth budget the viewer sets**, rather than spent at whatever rate the server would otherwise send. A ceiling chosen once — from the source's own bitrate down to a rung that still plays on a poor connection — governs every video the app opens, live TV included, and survives a restart, so a metered connection is not quietly drained by the next thing played. A single video can be moved to a different ceiling from the player, resuming where it was, without disturbing that default | Medium | Done |
 
 ---
@@ -406,6 +407,7 @@ Internal architecture, components, and application logic.
 | DR-214 | The app identifies itself correctly everywhere a user or a package manager reads its name. `productName` was the scaffold's lowercase `jellytau`, which is what the Android release build showed under its icon and what the deb/rpm/NSIS bundles carried as their display name — invisible in development because `build.gradle.kts` overrides the label to "JellyTau Debug" for the debug build type, so the install a developer looks at daily was the only correctly-cased one. `mainBinaryName` pins the executable filename so nothing that resolves a path by name has to change. `strings.xml` moves into the canonical android tree, where `sync-android-sources.sh` already copies `res/values/*.xml`, so the fix survives regenerating `gen/`. Bundle metadata (publisher, copyright, category, descriptions, licence) was entirely absent, which is why the packages shipped with no maintainer or description — the hand-written Arch PKGBUILD and `.desktop` had all of it, so only the *generated* packaging was wrong | Packaging | - | Done |
 | DR-215 | Frontend test coverage is a ratcheted CI gate rather than a number nobody looks at. `test:coverage` had been configured since the suite was created and was silently broken: `@vitest/coverage-v8` resolved to 4.1.10, whose peer range pins `vitest` exactly, while `package.json` asked for `>=1.0.0 <5.0.0` and got 4.0.16 — so every invocation died on a missing `BaseCoverageProvider` export and no coverage figure had been produced in months. Fixing the range is half the requirement; the other half is that a measured figure that gates nothing decays the same way an unrun script does. Thresholds sit a few points under the measured result (statements 54.6, branches 48.7, functions 49.6, lines 55.1 when this landed) and only ever move up, matching `MIN_THRESHOLD` in the traceability gate and the eslint `--max-warnings` ratchet. The absolute numbers are held down by `.svelte` components, which this project deliberately does not test directly — the pattern is to extract the logic to a plain module and test that | Tooling | - | Done |
 | DR-216 | Dependencies are gated on known vulnerabilities and on licence compatibility, and the build graph is pinned to what is actually shipped. The project had no scanning of any kind: nothing checked the ~500-crate Rust graph or the JS packages against an advisory feed, and nothing checked that everything redistributed inside an MIT-licensed bundle permits it. The first run found eight vulnerabilities and one unsoundness — `bytes`, four in `rustls-webpki`, `time`, two in `quick-xml`, `rand` — every one closed by a `cargo update` nobody had reason to run. `cargo deny` (src-tauri/deny.toml) now runs in CI over advisories, licences, bans and sources. Two structural fixes matter as much as the gate: the graph is scoped to the targets actually shipped, so an advisory against an Apple-only path is correctly absent rather than ignored by ID; and the one git dependency (`libmpv`) is pinned by revision instead of by branch, since a branch means any `cargo update` silently substitutes new upstream code in the one dependency that is unsigned and links a C library into the player. Licence findings are recorded rather than waved through — `libmpv`/`libmpv-sys` are LGPL-2.1, which the app satisfies by dynamic linking, and that carries obligations (keep the linkage dynamic; ship libmpv's licence text with any bundle carrying the .so) | Tooling | - | Done |
+| DR-217 | In-app update, desktop only, over a manifest we control. `tauri-plugin-updater` and `tauri-plugin-process` are compiled for everything except Android/iOS — spelled as a target-triple cfg rather than `cfg(desktop)`, which Cargo does not evaluate in a `[target.'cfg(…)']` table and which therefore drops the dependency silently, surfacing much later as "Permission updater:default not found". The release workflow signs updater artifacts with a minisign key held in Gitea secrets and publishes `latest.json` to a dedicated `updater` branch, read over Gitea's raw-file URL: this instance serves `/releases/download/<tag>/<asset>` but returns 404 for `/releases/latest/download/<asset>`, so there is no stable latest-release URL to point at, and the docs branch is force-pushed by publish-docs.yml so it cannot host the manifest either. Bundle targets gain `appimage`, which the release notes had been advertising for months while `tauri.conf.json` never built it — the artifact step globbed for `*.AppImage`, found nothing, and said nothing | Tooling | UR-077 | Done |
 | DR-198 | The webview runs under a real Content-Security-Policy, and the asset protocol is scoped to the one directory it still serves. `csp` was `null`, which disables CSP entirely: any script that reached the web layer — through a future `{@html}`, a dependency, or a devtools paste — would have inherited the whole IPC surface, and with it the user's session. `script-src 'self'` (Tauri injects a nonce for SvelteKit's inline bootstrap script at build time, so no `'unsafe-inline'` is needed) plus `object-src`/`frame-src 'none'` and `base-uri 'self'` is the part that is genuinely restrictive. `img-src`/`media-src`/`connect-src` cannot be: the Jellyfin origin is typed in by the user at run time and is commonly plain `http` on a LAN, so they allow `http:`/`https:` — a wide grant for *data*, but one that still bars `file:`, `filesystem:` and scripting schemes, and leaves `script-src` untouched. `style-src` keeps `'unsafe-inline'` because Svelte compiles `style="…"` attributes (including `app.html`'s `display: contents` wrapper) into markup; this is safe only while no `<style>` element survives into `index.html`, since a nonce there would make Tauri's injection outrank — and therefore void — `'unsafe-inline'`. `worker-src blob:` and `media-src blob:` are hls.js: it demuxes in a worker built from a blob and attaches MSE through `URL.createObjectURL`. `asset:` and `http://asset.localhost` are the same protocol under the two naming schemes `convertFileSrc` emits (custom scheme on Linux/macOS, `http` host on Windows/Android); `ipc:`/`http://ipc.localhost` is the invoke transport, which would otherwise be blocked by `connect-src`. A run-time CSP naming the server origin exactly was rejected: Tauri computes the header from immutable config when it serves the HTML, so it would mean rebuilding config and reloading the webview on every server change, for a policy the user can already point anywhere. The asset-protocol scope narrows from `$APPDATA/**` to `$APPDATA/thumbnails/**` — since DR-137 moved downloaded media to the loopback server, `imageCache` is the only `convertFileSrc` caller left, so the database and the encrypted-token fallback file no longer sit inside the grant | Security | UR-012, UR-071 | Done |
 
 ---
@@ -491,6 +493,7 @@ Internal architecture, components, and application logic.
 | UR-074 | - | DR-162, DR-177, DR-181 |
 | UR-075 | - | DR-174, DR-175 |
 | UR-076 | - | DR-209 |
+| UR-077 | - | DR-217 |
 
 ---
 
@@ -701,6 +704,7 @@ Internal architecture, components, and application logic.
 | UT-206 | The offline item-type filter is bound rather than interpolated (a value containing a quote and `OR 1=1` matches nothing instead of disabling the `WHERE`), `build_get_items_endpoint` percent-encodes its values while preserving the commas Jellyfin splits on, and volume normalisation clamps out-of-range input and maps NaN to a finite value | DR-212 | Done |
 | UT-200 | The stream a player could only restart is refused its retry: the handoff transcode answers yes to `player_retry_restarts_stream` while music, video and a downloaded episode answer no, and the Kotlin decision starts permissive, flips on a non-resumable load, and is restored by the next ordinary one | DR-203 | Done |
 | UT-207 | The hero banner's rotation timer restarts from the moment of a manual change: a swipe 5.5s into a 6s interval waits a further 6s instead of firing the leftover 500ms, repeated restarts never stack timers, and `stop()` ends rotation | DR-038 | Done |
+| UT-208 | The update decision: each numeric version field is compared in order, the installed version is not offered to itself, a leading `v` is tolerated because that is how the tags are written, a pre-release sorts below the release of the same number so 0.9.2-rc1 is not offered to somebody on 0.9.2, a missing patch field reads as zero rather than NaN, mobile reports link-only while desktop reports install, and absent release notes normalise to null rather than undefined | DR-217 | Done |
 
 ### Integration Tests