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/types/title.ts

@@ -58,4 +58,5 @@ export interface ResolvedTitle {
   voteCount: number | null;
   status: string | null;
   colorPalette: ColorPalette | null;
+  trailerVideoKey: string | null;
 }