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/theme/themes.dart

@@ -1,6 +1,6 @@
 import 'package:flutter/material.dart';
 
-/// Design tokens and themes for FixMate (Civic Pro Minimal)
+/// Design tokens and themes for CityPulse (Civic Pro Minimal)
 class AppColors {
   // Primary civic colors
   static const Color civicBlue = Color(0xFF2563EB);