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/components/FavoriteButton.svelte

@@ -1,27 +1,60 @@
+<!-- TRACES: UR-017, UR-068 | DR-021, DR-119 -->
 <script lang="ts">
   import { toggleFavorite } from "$lib/services/favorites";
   import { haptics } from "$lib/utils/haptics";
   import { toast } from "$lib/stores/toast";
+  import { favoriteOverrides } from "$lib/stores/favorites";
 
   interface Props {
     itemId: string;
     isFavorite?: boolean;
     size?: "sm" | "md" | "lg";
     className?: string;
+    /**
+     * "button" (default) is the standalone control used in header/hero rows;
+     * "overlay" is the artwork corner variant used on cards, which needs its
+     * own scrim to stay legible over any poster.
+     */
+    variant?: "button" | "overlay";
+    /** Stop the click reaching a parent card/row that would navigate or play. */
+    stopPropagation?: boolean;
   }
 
-  let { itemId, isFavorite = $bindable(false), size = "md", className = "" }: Props = $props();
+  let {
+    itemId,
+    isFavorite = $bindable(false),
+    size = "md",
+    className = "",
+    variant = "button",
+    stopPropagation = false,
+  }: Props = $props();
 
   let isLoading = $state(false);
   let isAnimating = $state(false);
 
+  // A toggle from any other surface (or the backend's `favorites-changed`
+  // refresh) wins over the prop we were mounted with — otherwise a heart tapped
+  // on a card would still read empty on the detail page behind it.
+  $effect(() => {
+    const override = $favoriteOverrides.get(itemId);
+    if (override !== undefined && override !== isFavorite) {
+      isFavorite = override;
+    }
+  });
+
   const sizeClasses = {
     sm: "w-4 h-4",
     md: "w-5 h-5",
     lg: "w-6 h-6",
   };
 
-  async function handleToggle() {
+  async function handleToggle(event: MouseEvent) {
+    // On a card the heart sits inside a clickable tile; without this, hearting
+    // an item would also open (or play) it.
+    if (stopPropagation) {
+      event.stopPropagation();
+      event.preventDefault();
+    }
     if (isLoading) return;
 
     isLoading = true;
@@ -55,8 +88,15 @@
 
   // Compute button classes
   const buttonClass = $derived.by(() => {
-    const baseClasses = "p-2 rounded-full transition-all";
-    const colorClasses = isFavorite ? "text-red-500 hover:text-red-400" : "text-gray-400 hover:text-white";
+    const baseClasses =
+      variant === "overlay"
+        ? "p-1.5 rounded-full transition-all bg-black/50 backdrop-blur-sm hover:bg-black/70"
+        : "p-2 rounded-full transition-all";
+    const colorClasses = isFavorite
+      ? "text-red-500 hover:text-red-400"
+      : variant === "overlay"
+        ? "text-white/80 hover:text-white"
+        : "text-gray-400 hover:text-white";
     const loadingClasses = isLoading ? "opacity-50 cursor-wait" : "";
     return `${baseClasses} ${colorClasses} ${loadingClasses} ${className}`.trim();
   });