fix(city): correct traffic signal orientation for right-hand traffic

- Fix vehicle signal head rotation to face approaching traffic correctly
- Refactor pedestrian signal positioning with descriptive naming
- Add getSignalHeads() method for snapshotting signal state
- Add cache-busting query parameter to app.js script tag

resources/views/city/viewer.blade.php

@@ -372,5 +372,5 @@
         citySlug: @json($city->slug),
     };
 </script>
-<script type="module" src="{{ asset('js/city/app.js') }}"></script>
+<script type="module" src="{{ asset('js/city/app.js') }}?v={{ filemtime(public_path('js/city/app.js')) }}"></script>
 @endpush