Finalize scoring system, release year integration, and fix song deletion

prisma/schema.prisma

@@ -16,6 +16,7 @@ model Song {
   artist    String
   filename  String   // Filename in public/uploads
   coverImage String?  // Filename in public/uploads/covers
+  releaseYear Int?   // Release year from MusicBrainz
   createdAt DateTime @default(now())
   puzzles   DailyPuzzle[]
   genres    Genre[]
@@ -62,7 +63,7 @@ model DailyPuzzle {
   id        Int      @id @default(autoincrement())
   date      String   // Format: YYYY-MM-DD
   songId    Int
-  song      Song     @relation(fields: [songId], references: [id])
+  song      Song     @relation(fields: [songId], references: [id], onDelete: Cascade)
   genreId   Int?
   genre     Genre?   @relation(fields: [genreId], references: [id])
   specialId Int?