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/lib/services/offlineCatalog.ts

@@ -66,9 +66,14 @@ function currentHandle(): string | null {
 }
 
 /**
- * Walk every library and cache the full catalog. Best-effort and non-blocking:
- * safe to call on startup (while online) and on reconnect. No-ops if not
- * connected or a sync is already running.
+ * Force a full re-index now, ignoring freshness.
+ *
+ * Routine scheduling is the Rust indexer's job (DR-109) — this is the manual
+ * override, for a "re-index now" affordance. It is deliberately *not* called on
+ * startup or reconnect any more: doing so forced a full crawl on every launch
+ * regardless of how fresh the index was.
+ *
+ * The backend refuses overlapping passes, so this is safe to call at any time.
  */
 export async function syncCatalog(): Promise<void> {
   if (syncInProgress) return;
@@ -124,6 +129,8 @@ export async function refreshSyncStatus(): Promise<void> {
  */
 export async function onReconnected(): Promise<void> {
   await resumeQueued();
-  // Fire-and-forget: don't block reconnection handling on a potentially long walk.
-  void syncCatalog();
+  // Re-indexing on reconnect is the Rust indexer's job (DR-109) — it re-checks
+  // staleness every tick, so it picks this up without a nudge from here. Queued
+  // downloads still need resolving from the frontend, which is why this
+  // function remains.
 }