fix(database): make playback session migration idempotent

lib/services/app_state_database.dart

@@ -103,8 +103,11 @@ class AppStateDatabase {
   }
 
   static Future<void> _createPlaybackSessionTable(Database db) {
+    // Keep this idempotent so an interrupted migration or a database restored
+    // from an intermediate build can resume v1 -> v2 without losing queue
+    // state merely because the table was already created.
     return db.execute('''
-      CREATE TABLE $_playbackSessionTable (
+      CREATE TABLE IF NOT EXISTS $_playbackSessionTable (
         id INTEGER PRIMARY KEY CHECK (id = 1),
         session_json TEXT NOT NULL,
         updated_at TEXT NOT NULL

test/models_and_utils_test.dart

@@ -139,6 +139,26 @@ void main() {
     });
   });
 
+  group('app state database migrations', () {
+    final source = File(
+      'lib/services/app_state_database.dart',
+    ).readAsStringSync();
+
+    test('v1 to v2 tolerates an existing playback session table', () {
+      expect(
+        source,
+        contains('CREATE TABLE IF NOT EXISTS \$_playbackSessionTable'),
+      );
+      expect(
+        RegExp(
+          r'if \(oldVersion < 2\)\s*\{\s*'
+          r'await _createPlaybackSessionTable\(db\);',
+        ).hasMatch(source),
+        isTrue,
+      );
+    });
+  });
+
   group('native worker contracts', () {
     final finalizerSource = File(
       'android/app/src/main/kotlin/com/zarz/spotiflac/'