fix(library): podcasts list newest episode first

A Jellypod podcast listed its episodes alphabetically. The store pinned
SortBy=SortName onto every drill-down, which overrode the order the
channel plugin returns — and since Jellypod prefixes played episodes with
"[Played]", the name sort also clumped every heard episode at the top.

Which order a container's children take is domain knowledge, so it moves
to Rust: the caller names the container (GetItemsOptions.parentKind) and
default_listing_sort answers with the sort. A channel folder is
PremiereDate descending, every other container keeps SortName ascending,
and a caller naming no container still gets no SortBy, so the paths that
rely on the server's own order keep it. An explicit sort always wins.

ChannelFolderItem with is_folder now maps to MediaKind::ChannelFolder
instead of collapsing into Folder — while both were Folder there was
nothing to key the rule on. The offline leg of the cache/server race
applies the same order, so the cached list no longer flashes in name
order before the server's arrives.

TRACES: UR-007 | DR-257 | UT-229, UT-230, UT-231

docs/requirements.md

@@ -450,6 +450,7 @@ Internal architecture, components, and application logic.
 | DR-254 | Advancing to the next episode drops a per-playback quality override. The override is process-wide and describes one playback: a viewer who drops to 720p for a struggling episode has said nothing about the next. Every advance the frontend drives clears it via `player_play_item`; the background audio-only advance loads the next episode in Rust and skipped all three clearing sites, so every later episode stayed capped with nothing in the UI saying why | Repository | UR-074 | Done |
 | DR-255 | One helper answers "what URL should an engine open". `playback_url` was gated to Android because only ExoPlayer needed it, and that gate is why a byte-identical copy was later added for the cross-platform open path — the original is invisible in a Linux build, so nothing warned. Two matches over `MediaSource` meant a new variant could be handled in one and forgotten in the other | Player | UR-081 | Done |
 | DR-256 | The video control bar opens **at most one menu at a time**, and opens it where it can be read. Audio track, quality and subtitles each owned a `show…` boolean that no other toggle cleared, so a second menu opened stacked over the first — two panels in the same corner, the newer one covering rows of the older, both still taking clicks. A single `openMenu` value replaces them, which makes "one menu" a property of the state rather than something every handler must remember; the desktop volume popup joins the same group through `VolumeControl`'s optional controlled-open props. Placement was the second half of the same defect: every panel was `absolute right-0` against **its own icon button**, and those icons sit mid-row, so a 220 px panel hung off the left edge of a portrait phone and half the tracks could not be read or tapped. One shared panel now anchors to the control ROW's right edge, clamped to `min(20rem, 100vw − 2rem)` wide and `min(300px, 45vh)` tall, with a full-screen dismiss layer inside the controls subtree so a tap elsewhere closes it without reaching the container's tap gestures (DR-098). The icon row itself wraps instead of overflowing — in portrait the transport controls plus nine icons are wider than the screen, which put fullscreen and close past the edge | UI | UR-020, UR-021, UR-066, UR-074 | Done |
+| DR-257 | A container's children are ordered by **what the container is**, decided in Rust. The frontend pinned `SortBy=SortName` onto every drill-down, so a Jellypod podcast — a Jellyfin channel folder whose plugin returns episodes newest-first and prefixes played ones with "[Played]" — listed alphabetically, which both discarded the release order and clumped every heard episode at the top. `ChannelFolderItem` with `is_folder` now maps to its own `MediaKind::ChannelFolder` rather than collapsing into `Folder`, which is what makes the two distinguishable at all; `default_listing_sort` maps that kind to `PremiereDate` descending and every other container to `SortName` ascending, and a caller that names no container still gets no `SortBy`, so paths relying on the server's own order (a playlist's stored order) keep it. An explicit sort always wins. The offline leg of the cache/server race applies the same order, so the cached list does not flash in name order before the server's arrives. The store now names the container and never a sort field — the ordering rule is domain vocabulary, the same division as `SearchScope` | Repository | UR-007 | 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 |
 
 ---
@@ -466,7 +467,7 @@ Internal architecture, components, and application logic.
 | UR-004 | IR-003, IR-004, IR-008, IR-011 | DR-002, DR-004, DR-006, DR-129, DR-171, DR-176, DR-177, DR-181, DR-182, DR-183, DR-185, DR-188, DR-203 |
 | UR-005 | - | DR-001, DR-005, DR-009, DR-178, DR-179, DR-186, DR-193, DR-195 |
 | UR-006 | IR-005, IR-006, IR-007, IR-008 | DR-200, DR-201 |
-| UR-007 | IR-010 | DR-007, DR-008, DR-016 |
+| UR-007 | IR-010 | DR-007, DR-008, DR-016, DR-257 |
 | UR-008 | IR-010 | DR-007, DR-011 |
 | UR-009 | IR-009, IR-010, IR-011 | - |
 | UR-010 | IR-012, IR-021 | DR-037, DR-059 |
@@ -770,6 +771,9 @@ Internal architecture, components, and application logic.
 | UT-226 | The background episode advance clears the per-playback quality override, so a ceiling chosen for one episode does not cap every episode after it | DR-254 | Done |
 | UT-227 | Opening any one of the control bar's menus closes whichever was open — track, quality, subtitle and the desktop volume popup are one group, never two panels at once — and a second click on the open menu's own toggle closes it | DR-256 | Done |
 | UT-228 | The open menu panel is anchored to the control row rather than to the icon that opened it, and carries a viewport-clamped width, so it cannot hang off the edge of a portrait screen | DR-256 | Done |
+| UT-229 | A channel folder's children are requested by release date, newest first, while every other container keeps name order; an explicit sort still wins, and a caller naming no container gets no `SortBy` at all | DR-257 | Done |
+| UT-230 | A `ChannelFolderItem` that is a folder maps to `ChannelFolder`, not to the generic `Folder` it was indistinguishable from | DR-257 | Done |
+| UT-231 | The library store sends the container's kind and no sort field, defaulting to a plain folder when the caller names none | DR-257 | Done |
 
 ### Integration Tests