feat: Add cover art support and auto-migration

- Extract cover art from MP3s during upload
- Display cover art in game result screens (win/loss)
- Add coverImage field to Song model
- Add migration script to backfill covers for existing songs
- Configure Docker to run migration script on startup

app/page.tsx

@@ -40,7 +40,10 @@ async function getDailyPuzzle() {
     return {
       id: dailyPuzzle.id,
       audioUrl: `/uploads/${dailyPuzzle.song.filename}`,
-      songId: dailyPuzzle.songId
+      songId: dailyPuzzle.songId,
+      title: dailyPuzzle.song.title,
+      artist: dailyPuzzle.song.artist,
+      coverImage: dailyPuzzle.song.coverImage ? `/uploads/covers/${dailyPuzzle.song.coverImage}` : null,
     };
   } catch (e) {
     console.error(e);