fix: Make transactions atomic / AutoLogout

test/app_lifecycle_lock_test.dart

@@ -0,0 +1,30 @@
+import 'package:flutter/widgets.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:kooltab2/app/app_lifecycle_lock.dart';
+
+void main() {
+  test('locks when the app is no longer active', () {
+    var lockCount = 0;
+    final observer = AppLifecycleLockObserver(onLock: () => lockCount++);
+
+    for (final state in [
+      AppLifecycleState.inactive,
+      AppLifecycleState.hidden,
+      AppLifecycleState.paused,
+      AppLifecycleState.detached,
+    ]) {
+      observer.didChangeAppLifecycleState(state);
+    }
+
+    expect(lockCount, 4);
+  });
+
+  test('does not lock while the app is active', () {
+    var lockCount = 0;
+    final observer = AppLifecycleLockObserver(onLock: () => lockCount++);
+
+    observer.didChangeAppLifecycleState(AppLifecycleState.resumed);
+
+    expect(lockCount, 0);
+  });
+}