fix: address code review findings

cmd/naviwatcher/main.go

@@ -49,7 +49,7 @@ func main() {
 		cancel()
 	}()
 
-	app, err := NewApp(ctx, cfg)
+	app, err := NewApp(ctx, cfg, "naviwatcher.db")
 	if err != nil {
 		log.Fatalf("Failed to initialize application: %v", err)
 	}
@@ -63,9 +63,10 @@ func main() {
 }
 
 // NewApp initializes all application components: config, database, and MusicBrainz client.
-func NewApp(ctx context.Context, cfg *config.Config) (*App, error) {
-	// Initialize database (uses default path or could be made configurable).
-	db, err := database.New("naviwatcher.db")
+// dbPath is the SQLite database path (use ":memory:" for tests).
+func NewApp(ctx context.Context, cfg *config.Config, dbPath string) (*App, error) {
+	// Initialize database.
+	db, err := database.New(dbPath)
 	if err != nil {
 		return nil, fmt.Errorf("failed to initialize database: %w", err)
 	}