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/player/localSource.test.ts

@@ -0,0 +1,73 @@
+import { describe, it, expect } from "vitest";
+import { resolveVideoSource } from "./localSource";
+
+// A stand-in for Tauri's convertFileSrc, so the module stays pure.
+const toAssetUrl = (p: string) => `asset://localhost/${encodeURIComponent(p)}`;
+
+describe("resolveVideoSource", () => {
+  it("plays the downloaded file when one exists", () => {
+    const decision = resolveVideoSource({
+      localPath: "/home/u/.local/share/jellytau/movie.mp4",
+      remoteUrl: "https://server/Videos/abc/master.m3u8",
+      remoteNeedsTranscoding: true,
+      toAssetUrl,
+    });
+
+    expect(decision.isLocal).toBe(true);
+    expect(decision.url).toBe(toAssetUrl("/home/u/.local/share/jellytau/movie.mp4"));
+  });
+
+  it("never marks a local file as needing transcoding, even when the remote did", () => {
+    // The transcoded path re-requests a whole new stream URL on every seek.
+    // A local file seeks natively; sending it down that route would ask the
+    // server for a stream we deliberately avoided.
+    const decision = resolveVideoSource({
+      localPath: "/downloads/film.mkv",
+      remoteUrl: "https://server/Videos/abc/master.m3u8",
+      remoteNeedsTranscoding: true,
+      toAssetUrl,
+    });
+
+    expect(decision.needsTranscoding).toBe(false);
+  });
+
+  it("streams when nothing is downloaded, preserving the transcoding flag", () => {
+    const decision = resolveVideoSource({
+      localPath: null,
+      remoteUrl: "https://server/Videos/abc/master.m3u8",
+      remoteNeedsTranscoding: true,
+      toAssetUrl,
+    });
+
+    expect(decision).toEqual({
+      url: "https://server/Videos/abc/master.m3u8",
+      needsTranscoding: true,
+      isLocal: false,
+    });
+  });
+
+  it("streams a direct-play remote without claiming it transcodes", () => {
+    const decision = resolveVideoSource({
+      localPath: null,
+      remoteUrl: "https://server/Videos/abc/stream.mp4",
+      remoteNeedsTranscoding: false,
+      toAssetUrl,
+    });
+
+    expect(decision.needsTranscoding).toBe(false);
+    expect(decision.isLocal).toBe(false);
+  });
+
+  it("falls back to streaming for a blank path rather than building a dead asset URL", () => {
+    for (const localPath of ["", "   "]) {
+      const decision = resolveVideoSource({
+        localPath,
+        remoteUrl: "https://server/stream",
+        remoteNeedsTranscoding: false,
+        toAssetUrl,
+      });
+      expect(decision.isLocal).toBe(false);
+      expect(decision.url).toBe("https://server/stream");
+    }
+  });
+});