feat(search): rank results by match quality and split TV/People groups

Neither search backend orders by *where* the query matched, so a mid-word hit
could outrank a prefix one — typing "parks" surfaced "Sparks of Love" above
"Parks and Recreation".

Add `domain/search_rank.rs`, which sorts by match position (prefix →
word-start → mid-word substring → no name match), then by media kind so a
container outranks its own contents. The sort is stable, so each backend's own
relevance still breaks ties it was never overruled on. `repository_search`
applies it to both the instant cache result and the merged cache+server union,
so the list does not reshuffle when server results land. Ranking lives in Rust
because "a better match" is domain vocabulary, not presentation.

On the frontend, the combined `tvShows` result group splits into separate
Shows and Episodes groups so a show no longer competes with its own episodes
for a slot, and a People group is added so searching an actor's name reaches
their bio. A stored `tvShows` order expands in place, keeping the position an
upgrading user chose for it.

src/lib/utils/searchScope.ts

@@ -66,47 +66,96 @@ export function resolveSearchScope(pathname: string): SearchScope {
 // Result groups
 // ---------------------------------------------------------------------------
 
-export type SearchGroupId = "songs" | "albums" | "artists" | "movies" | "tvShows";
+export type SearchGroupId =
+  | "shows"
+  | "episodes"
+  | "movies"
+  | "songs"
+  | "albums"
+  | "artists"
+  | "people";
 
-/** Shipped default order, per the spec. */
+/**
+ * Shipped default order.
+ *
+ * TRACES: UR-060 | DR-091
+ *
+ * Containers lead the kinds they contain — a show above its episodes, an album
+ * above nothing (songs are ranked separately) — which matches how people search:
+ * you look for the show, not an arbitrary episode of it. `people` sits last as
+ * a peripheral match; it exists so searching an actor's name reaches their bio
+ * page rather than silently dropping the result.
+ */
 export const DEFAULT_GROUP_ORDER: readonly SearchGroupId[] = [
+  "shows",
+  "episodes",
+  "movies",
   "songs",
   "albums",
   "artists",
-  "movies",
-  "tvShows",
+  "people",
 ];
 
 export const GROUP_LABELS: Record<SearchGroupId, string> = {
+  shows: "TV Shows",
+  episodes: "Episodes",
+  movies: "Movies",
   songs: "Songs",
   albums: "Albums",
   artists: "Artists",
-  movies: "Movies",
-  tvShows: "TV Shows",
+  people: "People",
 };
 
-/** Which scopes each group belongs to (`all` always includes everything). */
-const GROUP_SCOPE: Record<SearchGroupId, Exclude<SearchScope, "all">> = {
+/**
+ * Which scopes each group belongs to (`all` always includes everything).
+ *
+ * `people` maps to no narrow scope: cast/crew cut across music, film and TV, so
+ * it surfaces only under All rather than being forced into one of them.
+ */
+const GROUP_SCOPE: Record<SearchGroupId, Exclude<SearchScope, "all"> | null> = {
+  shows: "tv",
+  episodes: "tv",
+  movies: "movies",
   songs: "music",
   albums: "music",
   artists: "music",
-  movies: "movies",
-  tvShows: "tv",
+  people: null,
 };
 
 /** Item types that fall into each group. */
 const GROUP_ITEM_TYPES: Record<SearchGroupId, string[]> = {
+  shows: ["Series"],
+  episodes: ["Episode"],
+  movies: ["Movie"],
   songs: ["Audio"],
   albums: ["MusicAlbum"],
   artists: ["MusicArtist"],
-  movies: ["Movie"],
-  tvShows: ["Series", "Episode"],
+  people: ["Person"],
 };
 
 export function groupItemTypes(group: SearchGroupId): string[] {
   return [...GROUP_ITEM_TYPES[group]];
 }
 
+/**
+ * Stored group ids that no longer exist, mapped to the ids that replaced them.
+ *
+ * `tvShows` was one group holding both Series and Episode; it split so a show
+ * can outrank its own episodes. Expanding in place preserves the position the
+ * user chose for it.
+ *
+ * TRACES: UR-060 | DR-091
+ */
+const RETIRED_GROUP_IDS: Record<string, SearchGroupId[]> = {
+  tvShows: ["shows", "episodes"],
+};
+
+/** Resolve a stored id to the live id(s) it corresponds to, or none if unknown. */
+function migrateGroupId(id: string, known: Set<string>): SearchGroupId[] {
+  if (known.has(id)) return [id as SearchGroupId];
+  return RETIRED_GROUP_IDS[id] ?? [];
+}
+
 /**
  * Normalise a stored order into a usable one.
  *
@@ -123,11 +172,15 @@ export function normalizeGroupOrder(stored: unknown): SearchGroupId[] {
 
   if (Array.isArray(stored)) {
     for (const id of stored) {
-      if (typeof id !== "string" || !known.has(id)) continue;
-      const groupId = id as SearchGroupId;
-      if (seen.has(groupId)) continue;
-      seen.add(groupId);
-      order.push(groupId);
+      if (typeof id !== "string") continue;
+      // Retired ids expand in place rather than being dropped, so a user who
+      // dragged the old combined "TV Shows" group to the top keeps TV at the
+      // top instead of having shows/episodes appended to the bottom.
+      for (const groupId of migrateGroupId(id, known)) {
+        if (seen.has(groupId)) continue;
+        seen.add(groupId);
+        order.push(groupId);
+      }
     }
   }
 
@@ -143,6 +196,8 @@ export function groupsForScope(
   scope: SearchScope,
   order: readonly SearchGroupId[] = DEFAULT_GROUP_ORDER
 ): SearchGroupId[] {
+  // A `null` GROUP_SCOPE (people) belongs to no narrow scope, so it survives
+  // only under `all` — the `=== scope` test already excludes it elsewhere.
   return normalizeGroupOrder(order as SearchGroupId[]).filter(
     (id) => scope === "all" || GROUP_SCOPE[id] === scope
   );