feat(search): answer search from a local index; tier downloads by lifetime

Search's instant leg read only downloaded items, so with no downloads it
returned nothing and every keystroke fell through to a full Recursive=true
server query. It now reads the whole synced catalog through the same
availability CTE get_items uses, gated on the same include_catalog_browse
flag so search and browse cannot diverge. (UR-065, DR-108)

Also fixes three defects found while confirming that:

- items_fts grew by a full duplicate index every catalog pass. INSERT OR
  REPLACE fires no AFTER DELETE trigger without recursive_triggers, so the
  old index row was orphaned, and a TEXT PRIMARY KEY meant the replacement
  took a fresh rowid and inserted a second entry. Now a real upsert, with
  migration 021 rebuilding existing indexes. (DR-110)
- DELETE FROM items existed nowhere, so server-side deletions never
  propagated. Adds a post-crawl mark-and-sweep, scoped to crawled types,
  skipping downloaded items, and refusing to run after a partial crawl
  because items.parent_id cascades. (DR-110)
- The index omitted MusicArtist, Playlist and People, which search groups
  results by. Adds them plus people_fts (migration 022). (DR-111)

Re-indexing moves from a frontend startup call to a Rust background task
with a 6h TTL, so a long session no longer searches a stale catalog and a
restart no longer forces a crawl regardless of freshness. (DR-109, IR-030)

Downloads gain a lifetime tier. Eviction selected every completed row by
age with no download_source filter, so hitting the storage limit deleted
the oldest download -- typically one saved deliberately for offline -- to
make room for a precached track. It now reclaims only 'auto' rows, and
expired ones are reclaimed first, before live cache is evicted.
(DR-126, DR-127)

Downloaded video and audio-only handoffs now play from disk instead of
streaming; the video path had never consulted downloads at all. No
transcode is involved: MPV runs video=no and ExoPlayer has no surface for
an Audio item. (DR-123 in part, DR-128)

FTS queries are built as quoted phrases so apostrophes, hyphens and
slashes are data rather than operator syntax, and the item-type filter is
bound rather than interpolated.

Specs: docs/specs/catalog-index-search.md,
docs/specs/read-through-media-cache.md

Includes concurrently-developed favourites browsing and background-audio
stream-end handling; the two workstreams share offline.rs, lib.rs and
online.rs, so no subset of files builds independently.

src/routes/+layout.svelte

@@ -3,6 +3,7 @@
   import { get } from "svelte/store";
   import { page } from "$app/stores";
   import { platform } from "@tauri-apps/plugin-os";
+  import { listen, type UnlistenFn } from "@tauri-apps/api/event";
   import "../app.css";
   import { auth, needsReauth, isAuthenticated } from "$lib/stores/auth";
   import { connectivity, isConnected } from "$lib/stores/connectivity";
@@ -10,7 +11,8 @@
   import { initWebviewAudio, cleanupWebviewAudio } from "$lib/services/webviewAudio";
   import { downloads, initDownloadEvents, cleanupDownloadEvents } from "$lib/stores/downloads";
   import { syncService } from "$lib/services/syncService";
-  import { onReconnected as onCatalogReconnected, syncCatalog, refreshSyncStatus, showServerCatalog, lastCatalogSync } from "$lib/services/offlineCatalog";
+  import { clearFavorite } from "$lib/stores/favorites";
+  import { onReconnected as onCatalogReconnected, refreshSyncStatus, showServerCatalog, lastCatalogSync } from "$lib/services/offlineCatalog";
   import { playbackMode } from "$lib/stores/playbackMode";
   import { sessions } from "$lib/stores/sessions";
   import ReauthModal from "$lib/components/auth/ReauthModal.svelte";
@@ -34,6 +36,7 @@
 
   /** Teardown for the network-transport reporter (WiFi-only gate). */
   let stopNetworkReporting: (() => void) | null = null;
+  let stopFavoritesListener: UnlistenFn | null = null;
 
   /** Teardown for the native window-inset subscription (safe areas). */
   let stopSafeArea: (() => void) | null = null;
@@ -115,6 +118,18 @@
     // Initialize download event listener
     await initDownloadEvents();
 
+    // Favourite state can change behind the UI: another Jellyfin client marks
+    // something, or the Rust drain pushes toggles queued while offline. Drop
+    // the session overrides for those ids so the next render reads the freshly
+    // cached server value rather than a stale local guess.
+    // TRACES: UR-069 | DR-120
+    stopFavoritesListener = await listen<{ itemIds: string[] }>(
+      "favorites-changed",
+      (event) => {
+        for (const id of event.payload?.itemIds ?? []) clearFavorite(id);
+      }
+    );
+
     // Report the network transport to the backend and keep it current, so the
     // WiFi-only download gate has real data to act on (UR-053). No-op on
     // desktop, where the backend defaults to unmetered.
@@ -134,10 +149,10 @@
     // Start sync service for offline mutation queue
     syncService.start();
 
-    // Kick off a best-effort full-catalog pre-sync so the whole server catalog
-    // is browsable (greyed out) offline, and load the last-sync hint for the
-    // offline banner. Non-blocking — no-ops when not connected.
-    void syncCatalog();
+    // Load the last-sync hint for the offline banner. The catalog *index* is no
+    // longer kicked off from here: the Rust background indexer (DR-109) owns
+    // when to re-index, so a long session no longer searches a stale catalog and
+    // a restart no longer forces a full crawl regardless of freshness.
     void refreshSyncStatus();
 
     // Initialize playback mode and session monitoring
@@ -147,6 +162,8 @@
 
   onDestroy(() => {
     stopNetworkReporting?.();
+    stopFavoritesListener?.();
+    stopFavoritesListener = null;
     stopSafeArea?.();
     cleanupPlayerEvents();
     cleanupWebviewAudio();