Add watch trailer button with cinematic YouTube player dialog

Fetch trailer video keys from TMDB videos API during title import/refresh,
store in DB, and display a "Trailer" button on title pages that opens a
media-chrome Sutro-themed YouTube player in a fullwidth dialog.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/tmdb/client.ts

@@ -7,6 +7,7 @@ import type {
   TmdbSearchResponse,
   TmdbSeasonDetails,
   TmdbTvDetails,
+  TmdbVideosResponse,
   TmdbWatchProviderResponse,
 } from "./types";
 
@@ -141,6 +142,10 @@ export async function discover(
   );
 }
 
+export async function getVideos(tmdbId: number, type: "movie" | "tv") {
+  return tmdbFetch<TmdbVideosResponse>(`/${type}/${tmdbId}/videos`);
+}
+
 export async function findByExternalId(
   externalId: string,
   source: "imdb_id" | "tvdb_id",