- Refactor Embedding Model Download to use WorkManager

- Move LLM service binding to MainActivity to comply with Android 14+ requirements.
- Remove the explicit embedding model setup screen, initiating the download in the background instead.
- Update the RAG creation screen to check for and notify the user about the ongoing download status.
- Add a database migration to include new fields in the `installed_rags` table.

Author: Saumesh425

app/src/main/java/com/dark/tool_neuron/database/AppDatabase.kt

@@ -17,7 +17,7 @@ import com.dark.tool_neuron.models.table_schema.ModelConfig
 
 @Database(
     entities = [Model::class, ModelConfig::class, InstalledRag::class],
-    version = 3,
+    version = 4,
     exportSchema = false
 )
 @TypeConverters(Converters::class)
@@ -67,14 +67,61 @@ abstract class AppDatabase : RoomDatabase() {
             }
         }
 
+        private val MIGRATION_3_4 = object : Migration(3, 4) {
+            override fun migrate(db: SupportSQLiteDatabase) {
+                // Recreate installed_rags table without DEFAULT constraints in SQL
+                // Room expects defaults to be handled at the application level, not database level
+
+                // Create new table with correct schema (no DEFAULT clauses)
+                db.execSQL("""
+                    CREATE TABLE IF NOT EXISTS installed_rags_new (
+                        id TEXT PRIMARY KEY NOT NULL,
+                        name TEXT NOT NULL,
+                        description TEXT NOT NULL,
+                        source_type TEXT NOT NULL,
+                        file_path TEXT,
+                        node_count INTEGER NOT NULL,
+                        embedding_dimension INTEGER NOT NULL,
+                        embedding_model TEXT NOT NULL,
+                        domain TEXT NOT NULL,
+                        language TEXT NOT NULL,
+                        version TEXT NOT NULL,
+                        tags TEXT NOT NULL,
+                        status TEXT NOT NULL,
+                        is_enabled INTEGER NOT NULL,
+                        created_at INTEGER NOT NULL,
+                        updated_at INTEGER NOT NULL,
+                        last_loaded_at INTEGER,
+                        size_bytes INTEGER NOT NULL,
+                        metadata_json TEXT,
+                        is_encrypted INTEGER NOT NULL,
+                        loading_mode INTEGER NOT NULL,
+                        has_admin_access INTEGER NOT NULL
+                    )
+                """.trimIndent())
+
+                // Copy data from old table to new table
+                db.execSQL("""
+                    INSERT INTO installed_rags_new
+                    SELECT * FROM installed_rags
+                """.trimIndent())
+
+                // Drop old table
+                db.execSQL("DROP TABLE installed_rags")
+
+                // Rename new table to original name
+                db.execSQL("ALTER TABLE installed_rags_new RENAME TO installed_rags")
+            }
+        }
+
         fun getDatabase(context: Context): AppDatabase {
             return INSTANCE ?: synchronized(this) {
                 val instance = Room.databaseBuilder(
                     context.applicationContext,
                     AppDatabase::class.java,
                     "llm_models_database"
                 )
-                    .addMigrations(MIGRATION_1_2, MIGRATION_2_3)
+                    .addMigrations(MIGRATION_1_2, MIGRATION_2_3, MIGRATION_3_4)
                     .fallbackToDestructiveMigration()
                     .build()
                 INSTANCE = instance