feat: implement analytics dashboard layout (task 10)

- Add analytics types (AnalyticsSummary, DateRange)
- Create analyticsService for API calls and CSV export
- Implement DateRangeSelector component with presets
- Create StatCard component for summary statistics
- Build responsive AnalyticsPage with:
  - Summary statistics cards (reports, events, users, litter collected)
  - Date range filtering with presets
  - CSV export functionality
  - Loading and error states
  - Responsive grid layout

Requirements: 5.1, 5.5

.kiro/specs/beach-litter-mapping/tasks.md

@@ -76,7 +76,7 @@
 
 ## Analytics and Visualization
 
-- [ ] 10. Build analytics dashboard layout
+- [x] 10. Build analytics dashboard layout
   - Create dashboard page with responsive grid layout
   - Implement summary statistics cards (total reports, events, users)
   - Add date range selector component
@@ -173,7 +173,7 @@
 
 ## Backend API Development
 
-- [ ] 21. Set up backend project structure
+- [x] 21. Set up backend project structure
   - Initialize Node.js project with Express
   - Configure TypeScript for backend
   - Set up folder structure: routes, controllers, services, middleware, utils