detect dirty container title and comment, rewrite to canonical form

Track format.tags.title and format.tags.comment on media_items via a new
containerTitle() helper producing "Name (Year)" for movies and
"Series (Year) - S01E02 - Title" for episodes. Analyzer and
recomputePlanAfterToggle now flag non-canonical container title and
non-empty comment as non-noop ("Fix container title", "Clear comment"),
and verifyDesiredState checks them post-ffmpeg. buildStreamFlags writes
the canonical title and clears comment on every run.

Existing libraries need a rescan to populate the new columns.

server/types.ts

@@ -19,6 +19,8 @@ export interface MediaItem {
 	imdb_id: string | null;
 	tmdb_id: string | null;
 	tvdb_id: string | null;
+	container_title: string | null;
+	container_comment: string | null;
 	scan_status: "pending" | "scanned" | "error";
 	scan_error: string | null;
 	last_scanned_at: string | null;