feat(library): focused music/TV/movie landing screens + self-draining download queue

Library screens:
- Add dedicated music, TV, and movie landing pages (hero banner +
  horizontal carousels) backed by new music/tv/movies stores.
- Route tvshows libraries to /library/tv; surface rediscover ("haven't
  listened to in a while") albums via a new repository method across
  online/offline/hybrid repos plus the repository_get_rediscover_albums
  command.
- Add an A-Z jump bar for long alphabetically-sorted lists, with grid
  index anchors in LibraryGrid/LibraryListView/TrackList.
- Filter the "Podcasts" folder out of music library queries.

Downloads:
- Add a backend queue pump: enqueue_download / enqueue_video_downloads
  persist the resolved stream URL + target dir on each row (migration
  017), and the pump starts up to max_concurrent and drains the rest
  automatically as slots free, instead of the frontend silently dropping
  items past the concurrency limit. Album/series/season buttons now
  enqueue rather than calling start_download directly.

Other fixes:
- Hybrid search now returns instant cache results and pushes the merged
  cache+server union via a request-id-tagged search-event, so superseded
  queries can't clobber fresher results.
- URL-encode SearchTerm / genres / item types in online repo requests.
- Android: pause on audio-becoming-noisy (headphone/BT disconnect).

src/lib/api/bindings.ts

@@ -726,6 +726,31 @@ async markDownloadFailed(downloadId: number, errorMessage: string) : Promise<nul
 async startDownload(downloadId: number, streamUrl: string, targetDir: string) : Promise<null> {
     return await TAURI_INVOKE("start_download", { downloadId, streamUrl, targetDir });
 },
+/**
+ * Enqueue a download with its resolved stream URL, then let the queue pump
+ * start it (or a higher-priority pending item) when a slot is free.
+ * 
+ * Unlike [`start_download`], this never errors when the concurrency limit is
+ * reached: the URL is persisted on the row and the pump will pick it up once a
+ * slot frees. This is the path bulk operations (album/series/season) use so
+ * every queued item eventually downloads without the frontend re-issuing it.
+ */
+async enqueueDownload(downloadId: number, streamUrl: string, targetDir: string) : Promise<null> {
+    return await TAURI_INVOKE("enqueue_download", { downloadId, streamUrl, targetDir });
+},
+/**
+ * Enqueue a batch of already-queued video downloads, resolving each one's
+ * transcode URL from the repository using the `quality_preset` stored on the
+ * row. Then let the pump start them subject to the concurrency limit.
+ * 
+ * This is the bulk video path (series/season): `download_series`/
+ * `download_season` insert the rows, then this resolves URLs and enqueues them
+ * so they actually start. Resolving server-side avoids round-tripping every
+ * episode URL through the frontend.
+ */
+async enqueueVideoDownloads(handle: string, downloadIds: number[], targetDir: string) : Promise<null> {
+    return await TAURI_INVOKE("enqueue_video_downloads", { handle, downloadIds, targetDir });
+},
 /**
  * Get download manager statistics
  */
@@ -1037,6 +1062,12 @@ async repositoryGetRecentlyPlayedAudio(handle: string, limit: number | null) : P
 async repositoryGetResumeMovies(handle: string, limit: number | null) : Promise<MediaItem[]> {
     return await TAURI_INVOKE("repository_get_resume_movies", { handle, limit });
 },
+/**
+ * Get albums the user hasn't listened to recently ("rediscover")
+ */
+async repositoryGetRediscoverAlbums(handle: string, parentId: string | null, limit: number | null) : Promise<MediaItem[]> {
+    return await TAURI_INVOKE("repository_get_rediscover_albums", { handle, parentId, limit });
+},
 /**
  * Get genres for a library
  */
@@ -1046,8 +1077,8 @@ async repositoryGetGenres(handle: string, parentId: string | null) : Promise<Gen
 /**
  * Search for items
  */
-async repositorySearch(handle: string, query: string, options: SearchOptions | null) : Promise<SearchResult> {
-    return await TAURI_INVOKE("repository_search", { handle, query, options });
+async repositorySearch(handle: string, query: string, options: SearchOptions | null, requestId: number) : Promise<SearchResult> {
+    return await TAURI_INVOKE("repository_search", { handle, query, options, requestId });
 },
 /**
  * Get playback info for an item