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/player/[id]/+page.svelte

@@ -4,6 +4,7 @@
   import { goto } from "$app/navigation";
   import { convertFileSrc } from "@tauri-apps/api/core";
   import { commands } from "$lib/api/bindings";
+  import { resolveVideoSource } from "$lib/player/localSource";
   import type { PlayQueueRequest } from "$lib/api/bindings";
   import type { MediaItem, MediaKind } from "$lib/api/types";
   import { auth } from "$lib/stores/auth";
@@ -299,11 +300,28 @@
           // Playback API now detects HEVC/10-bit and returns transcoded URL when needed
           console.log("loadAndPlay: Using video stream, directPlay:", playbackInfo.directPlay, "needsTranscoding:", playbackInfo.needsTranscoding);
           mediaSourceId = playbackInfo.mediaSourceId;
-          videoNeedsTranscoding = playbackInfo.needsTranscoding;
 
-          // Use the stream URL from playback info (already transcoded if needed)
-          streamUrl = playbackInfo.streamUrl;
-          console.log("loadAndPlay: Using stream URL:", streamUrl);
+          // Prefer a completed download over streaming. Audio has done this
+          // since the queue is built; video previously always streamed, so a
+          // downloaded film re-spent bandwidth already spent and would not play
+          // at all offline. Rust returns null when nothing is downloaded or the
+          // file has gone, so this falls back to the server on its own.
+          // TRACES: UR-071 | DR-123
+          const localPath = await commands.playerLocalMediaPath(id);
+          const source = resolveVideoSource({
+            localPath,
+            remoteUrl: playbackInfo.streamUrl,
+            remoteNeedsTranscoding: playbackInfo.needsTranscoding,
+            toAssetUrl: convertFileSrc,
+          });
+
+          streamUrl = source.url;
+          videoNeedsTranscoding = source.needsTranscoding;
+          console.log(
+            source.isLocal
+              ? "loadAndPlay: Playing downloaded file from disk"
+              : `loadAndPlay: Using stream URL: ${streamUrl}`
+          );
 
           // Set initial position for video player to seek to after load
           // Use explicit startPosition, or fall back to retrieved progress from database