simplified code across the app and consolidated duplicated helpers

lib/push/push_tap_router.dart

@@ -1,4 +1,3 @@
-import 'dart:convert';
 import 'dart:developer';
 
 import 'package:flutter/foundation.dart';
@@ -25,7 +24,7 @@ class PushTapRouter {
       PushActions.handleBackgroundResponse(response);
       return;
     }
-    final map = _payloadMap(response.payload);
+    final map = decodeNotificationPayload(response.payload);
     if (map == null) return;
     final target = resolvePushTarget(map);
     if (target != null) pendingTarget.value = target;
@@ -50,13 +49,4 @@ class PushTapRouter {
       log('Reading the notification launch details failed: $e');
     }
   }
-
-  static Map<String, dynamic>? _payloadMap(String? payload) {
-    if (payload == null || payload.isEmpty) return null;
-    try {
-      return jsonDecode(payload) as Map<String, dynamic>;
-    } on Object {
-      return null;
-    }
-  }
 }