feat: add gallery feature with database integration and rendering capabilities

lib/providers/backend_status_provider.dart

@@ -0,0 +1,42 @@
+import "dart:async";
+
+import "package:flutter/foundation.dart";
+import "package:quotegen_client/services/quote_api_v2.dart";
+
+
+// tracks whether the render backend is reachable, so the ui can hide stuff
+// that actually needs it (video render, snapshot links etc) when its down
+class BackendStatusProvider extends ChangeNotifier {
+
+  // start optimistic - dont want everything flashing away before the first check lands
+  bool isOnline = true;
+  bool hasChecked = false;
+
+  Timer? _pollTimer;
+  bool _disposed = false;
+
+  BackendStatusProvider() {
+    checkNow();
+    _pollTimer = Timer.periodic(const Duration(seconds: 15), (_) => checkNow());
+  }
+
+  Future<void> checkNow() async {
+    final online = await QuoteGeneratorApiV2.checkHealth();
+
+    if (_disposed) return;
+
+    hasChecked = true;
+
+    if (online != isOnline) {
+      isOnline = online;
+      notifyListeners();
+    }
+  }
+
+  @override
+  void dispose() {
+    _disposed = true;
+    _pollTimer?.cancel();
+    super.dispose();
+  }
+}