feat: implement hotspot visualization on map
- Add HotspotSeverity type and HotspotWithSeverity interface
- Implement getHotspots() method in analyticsService with severity calculation
- Add hotspot layer to MapView component with color-coded circles
- Create hotspot markers with severity icons and report count badges
- Add detailed hotspot popups showing report count, severity score, radius, and dates
- Implement hotspot toggle control in MapFilters with loading state
- Add hotspot severity legend to MapFilters
- Integrate hotspot data fetching in MapPage with sample fallback data
- Color-code hotspot boundaries: yellow (low), orange (medium/high), red (critical)
- Display hotspot statistics in interactive popups
Implements task 12: Create hotspot visualization
Requirements: 3.2, 3.3, 3.5
Paul Bailey
40a96142ba