feat(plex): person cards in the grid for the filtered actors (S3)

The actors currently in the filter now render as cards above the poster grid —
headshot + name + in-scope title count + a remove x — so you SEE who you're
exploring, not just chips in the rail (generalises the old search-only person
cards to the applied filter). New GET /plex/people/cards (photo from the
plex_people cache, count live against cast_names); PlexBrowse fetches + renders
them; i18n en/hu. Verified: John Goodman (11) / Douglas M. Griffin (1) / Bradley
Cooper (14) with photos + counts. (Plex cast-explore S3)

frontend/src/lib/api.ts

@@ -828,6 +828,11 @@ export interface PlexCastMember {
   role?: string | null;
   thumb?: string | null; // proxied person-image url, or null when Plex has no photo
 }
+export interface PlexPersonCard {
+  name: string;
+  photo?: string | null; // proxied person-image url, or null (placeholder)
+  count: number; // in-scope movies/shows featuring them
+}
 // The expanded Plex browse filters (movie libraries). Persisted per-account as JSON.
 export interface PlexFilters {
   genres: string[];
@@ -1351,6 +1356,9 @@ export const api = {
     req(`/api/plex/season/${encodeURIComponent(rk)}/state`, { method: "POST", body: JSON.stringify({ watched }) }),
   plexItem: (id: string): Promise<PlexItemDetail> =>
     req(`/api/plex/item/${encodeURIComponent(id)}`),
+  // Cards for the actor filter-chips currently applied: name + cached headshot + in-scope film/show count.
+  plexPeopleCards: (names: string[], scope: string): Promise<{ people: PlexPersonCard[] }> =>
+    req(`/api/plex/people/cards?scope=${encodeURIComponent(scope)}&names=${encodeURIComponent(names.join(","))}`),
   plexSession: (id: string, start = 0, audio?: number | null, aoff = 0, multi = false): Promise<PlexPlaySession> => {
     const p = new URLSearchParams({ start: String(Math.max(0, Math.floor(start))) });
     if (audio != null) p.set("audio", String(audio));