fix(player): play on past the end of a season

Autoplay listed the episodes of the current season and stopped dead at the
last one, so the end of a season returned AutoplayDecision::Stop. On the
Android background-audio handoff that is felt as playback simply pausing
mid-binge with the screen locked and no UI to un-pause it -- the device log
reads "Current episode is the last in the season" and then "Decision: Stop
playback", one episode after a mid-season boundary the backend advanced
through by itself.

The lookup now walks the series' seasons and takes the first episode of the
next one that has any. Seasons are sorted client-side by index number
because the offline repository ignores sort_by, empty seasons are skipped
rather than read as the end of the series, and Specials are never rolled
into: Jellyfin numbers them 0 so they sort ahead of season 1, but a server
that leaves the index unset sorts them last, exactly where the walk would
otherwise land.

Every autoplay entry point shares this lookup, so foreground video and the
Android native path cross the boundary too. It stays below the sleep-timer
gate in on_playback_ended, so a timer set to end-of-episode or a remaining
episode count still stops at the boundary instead of being carried past it.

TRACES: UR-023, UR-040 | DR-263 | UT-238

docs/requirements.md

@@ -456,6 +456,7 @@ Internal architecture, components, and application logic.
 | DR-260 | Subtitle cues are **drawn**. ExoPlayer decodes subtitles and delivers them to a listener; it draws none of them itself, and native video here is a bare `TextureView` the WebView composites over rather than a `PlayerView`, so nothing was holding the cues and a selected track rendered nowhere. The gap was invisible while every subtitle URL 404ed (DR-259) — with no text track to select there was never a cue to drop, so fixing the URL is what exposed it. `media3-ui`'s `SubtitleView` now takes each `CueGroup` from `onCues` and is attached at index 1 of the content view: above the video, still below the WebView, so cues sit over the picture and under the app's own controls. It is fitted to the letterboxed video rect rather than the screen, so cues stay inside the picture and follow it on rotation, and is torn down with the surface it belongs to. Verified on a device | Player | UR-020, UR-003 | Done |
 | DR-261 | Subtitles are drawn **over the picture, not on a black bar across it**. `SubtitleView.setUserDefaultStyle()` reads Android's captioning preferences and falls back to media3's `DEFAULT` when the viewer has set none — and that default is white on opaque black, so every line arrived in a box as wide as the text. The viewer's own style is kept and only the two colours that paint a box, background and window, are cleared: someone who has configured captions in accessibility settings has said something specific about colour, typeface and edges, and replacing all of it to remove a background would answer a question they did not ask. A style specifying no edge gets a black outline, because without a box the text must supply its own contrast or it is unreadable over a bright scene; a style that already names an edge keeps it | Player | UR-020 | Done (pending device verification) |
 | DR-262 | The A-Z jump strip is bounded by the **scroller it lives in**, not by the viewport minus a guess at the bottom bars. `AlphabetScrollBar` sized itself as `window.innerHeight` minus a hardcoded `bottomGap` — 5rem, 7rem or 11rem, picked by platform and whether the mini player was showing — which dates from when the mini player and bottom nav were `position: fixed` overlays. They have been in-flow flex siblings below the scroller since BottomUi (DR-009), so the scroller's own bottom edge *is* the top of the mini player and can simply be measured. The guess was short on every device with a navigation or gesture bar, because `--safe-bottom` is padded *inside* BottomUi (DR-112) and no guess knew about it: the strip overran the scrollport by ~45px with the nav alone, ~18px with the mini player and ~50px in remote mode, burying one to three letters where they could not be tapped. The ancestor is resolved by computed `overflow-y` rather than `closest("main")`, since the root shell scrolls in a plain `<div>` and a miss silently fell back to the viewport — reinstating the bug on any route outside `/library`. Observing the scroller for resize is also what makes the mini player appearing re-measure, so the component no longer subscribes to player or platform stores at all | UI | UR-007 | Done |
+| DR-263 | Autoplay crosses the **season boundary**. `fetch_next_episode_for_item` listed the episodes of the current season and stopped dead at the last one, so the end of a season produced `AutoplayDecision::Stop`. On the Android background-audio handoff (UR-040) that is felt as playback simply pausing mid-binge with the screen locked and no UI to un-pause it — the same end that mid-season advances through in the backend. The lookup now walks the series' seasons, sorted client-side by index number because the offline repository ignores `sort_by`, and takes the first episode of the next season that has any, skipping empty ones. Specials are never rolled *into*: Jellyfin numbers them 0 so they sort ahead of season 1, but a server that leaves the index unset sorts them last, exactly where the walk would land. The lookup sits below the sleep-timer gate in `on_playback_ended`, so a timer set to end-of-episode or a remaining-episode count still stops at the boundary rather than being carried past it | Player | UR-023, UR-040 | 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 |
 
 ---
@@ -488,7 +489,7 @@ Internal architecture, components, and application logic.
 | UR-020 | IR-016, IR-018 | DR-023, DR-176 |  <!-- IR-018 delivered by ExoPlayer + HTML5 `<track>`, not libmpv -->
 | UR-021 | IR-016, IR-019 | DR-024 |  <!-- IR-019 delivered by ExoPlayer + HLS stream re-open, not libmpv -->
 | UR-022 | IR-017 | DR-025 |
-| UR-023 | IR-010 | DR-026, DR-047, DR-048, DR-049 |
+| UR-023 | IR-010 | DR-026, DR-047, DR-048, DR-049, DR-263 |
 | UR-024 | IR-010 | DR-027 |
 | UR-025 | IR-015 | DR-028, DR-131, DR-132, DR-178, DR-179 |
 | UR-026 | - | DR-029, DR-048, DR-050 |
@@ -505,7 +506,7 @@ Internal architecture, components, and application logic.
 | UR-037 | IR-010 | DR-042 |
 | UR-038 | IR-010 | DR-043 |
 | UR-039 | - | DR-045, DR-046 |
-| UR-040 | IR-025 | DR-051, DR-052, DR-129, DR-130, DR-159, DR-178, DR-179, DR-180, DR-183, DR-190, DR-196, DR-201, DR-203 |
+| UR-040 | IR-025 | DR-051, DR-052, DR-129, DR-130, DR-159, DR-178, DR-179, DR-180, DR-183, DR-190, DR-196, DR-201, DR-203, DR-263 |
 | UR-041 | IR-026 | DR-053, DR-160, DR-161, DR-172, DR-182, DR-183, DR-184, DR-185, DR-188 |
 | UR-042 | IR-009, IR-014 | DR-054 |
 | UR-043 | IR-027 | DR-055 |
@@ -785,6 +786,7 @@ Internal architecture, components, and application logic.
 | UT-235 | The A-Z strip's last letter stays above the bottom nav, above the mini player while audio plays, and above the taller remote-mode mini player | DR-262 | Done |
 | UT-236 | The strip still fills the space it does have rather than stopping a letter short | DR-262 | Done |
 | UT-237 | The strip falls back to the viewport with no scroll container, and never computes a negative height when scrolled past its floor | DR-262 | Done |
+| UT-238 | The last episode of a season rolls over into the first of the next, skips an empty season on the way, and still stops there when the sleep timer says so | DR-263 | Done |
 
 ### Integration Tests