chore(branding): rebrand FixMate to CityPulse across codebase

- Update product name in README, backend docs, and design tokens
- Rename Flutter root widget to CityPulseApp and update tests
- Update dashboard brand strings and HTML title
- Refresh i18n strings (en/ms) and welcome taglines
- Adjust backend API title/description and root message
- Minor formatting in ApiService comments; no logic changes
- Update Android/iOS manifest comments and pubspec description

No API endpoints or response schema changes.

lib/app.dart

@@ -10,8 +10,8 @@ import 'screens/settings/settings_screen.dart';
 import 'theme/themes.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 
-class FixMateApp extends StatelessWidget {
-  const FixMateApp({super.key});
+class CityPulseApp extends StatelessWidget {
+  const CityPulseApp({super.key});
 
   @override
   Widget build(BuildContext context) {