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.

dashboard/i18n/ms.json

@@ -1,5 +1,5 @@
 {
-  "dashboard.brand": "FixMate",
+  "dashboard.brand": "CityPulse",
   "dashboard.filters": "Penapis",
   "queue.title": "Tiket",
   "drawer.details": "Maklumat",