fix(android): provide AudioCacheIndexDao to Hilt graph

The offline-pool ShuffleSource (2a87a50b) injects AudioCacheIndexDao,
but DatabaseModule had no @Provides bridge for it — nothing had
injected that DAO via Hilt before, so the graph was missing the
binding and hiltJavaCompileDebug failed. Added the provider.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

android/app/src/main/java/com/fabledsword/minstrel/cache/db/DatabaseModule.kt

@@ -2,6 +2,7 @@ package com.fabledsword.minstrel.cache.db
 
 import android.content.Context
 import androidx.room.Room
+import com.fabledsword.minstrel.cache.db.dao.AudioCacheIndexDao
 import com.fabledsword.minstrel.cache.db.dao.AuthSessionDao
 import com.fabledsword.minstrel.cache.db.dao.CachedAlbumDao
 import com.fabledsword.minstrel.cache.db.dao.CachedArtistDao
@@ -87,5 +88,10 @@ object DatabaseModule {
     @Singleton
     fun provideSyncMetadataDao(db: AppDatabase): SyncMetadataDao = db.syncMetadataDao()
 
+    @Provides
+    @Singleton
+    fun provideAudioCacheIndexDao(db: AppDatabase): AudioCacheIndexDao =
+        db.audioCacheIndexDao()
+
     private const val DATABASE_NAME = "minstrel.db"
 }