Phase 3.1: Local notification for WS chat requests, router fix, cleanup

- Show local notification (sound + vibrate) when chat_request arrives
  via WebSocket while mitra app is backgrounded
- Add NotificationService.showLocalNotification() for programmatic use
- Fix router redirect: don't redirect auth routes to splash during loading
- Handle binary/string WebSocket frames in ChatRequestNotifier
- Remove debug logging from backend and Flutter
- Control center: mitra ping config UI
- Both apps: dynamic ping, FCM deep-linking, unread badges

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

mitra_app/lib/core/notifications/notification_service.dart

@@ -83,6 +83,36 @@ class NotificationService {
     _navigateFromMessage(message.data);
   }
 
+  /// Show a local notification programmatically (e.g. from WebSocket while backgrounded)
+  static Future<void> showLocalNotification({
+    required String title,
+    required String body,
+    Map<String, dynamic>? data,
+  }) async {
+    await _localNotifications.show(
+      id: DateTime.now().millisecondsSinceEpoch % 100000,
+      title: title,
+      body: body,
+      notificationDetails: NotificationDetails(
+        android: AndroidNotificationDetails(
+          _channel.id,
+          _channel.name,
+          channelDescription: _channel.description,
+          importance: Importance.high,
+          priority: Priority.high,
+          playSound: true,
+          enableVibration: true,
+        ),
+        iOS: const DarwinNotificationDetails(
+          presentAlert: true,
+          presentBadge: true,
+          presentSound: true,
+        ),
+      ),
+      payload: data != null ? jsonEncode(data) : null,
+    );
+  }
+
   static void _navigateFromMessage(Map<String, dynamic> data) {
     if (_router == null) return;
     final sessionId = data['session_id'] as String?;