feat: implement comprehensive gamification, analytics, and leaderboard system

This commit adds a complete gamification system with analytics dashboards,
leaderboards, and enhanced badge tracking functionality.

Backend Features:
- Analytics API with overview, user stats, activity trends, top contributors,
  and street statistics endpoints
- Leaderboard API supporting global, weekly, monthly, and friends views
- Profile API for viewing and managing user profiles
- Enhanced gamification service with badge progress tracking and user stats
- Comprehensive test coverage for analytics and leaderboard endpoints
- Profile validation middleware for secure profile updates

Frontend Features:
- Analytics dashboard with multiple tabs (Overview, Activity, Personal Stats)
- Interactive charts for activity trends and street statistics
- Leaderboard component with pagination and timeframe filtering
- Badge collection display with progress tracking
- Personal stats component showing user achievements
- Contributors list for top performing users
- Profile management components (View/Edit)
- Toast notifications integrated throughout
- Comprehensive test coverage for Leaderboard component

Enhancements:
- User model enhanced with stats tracking and badge management
- Fixed express.Router() capitalization bug in users route
- Badge service improvements for better criteria matching
- Removed unused imports in Profile component

This feature enables users to track their contributions, view community
analytics, compete on leaderboards, and earn badges for achievements.

🤖 Generated with OpenCode

Co-Authored-By: AI Assistant <noreply@opencode.ai>

frontend/package.json

@@ -17,6 +17,7 @@
     "react-router-dom": "^6.28.0",
     "react-scripts": "5.0.1",
     "react-toastify": "^11.0.5",
+    "recharts": "^3.3.0",
     "socket.io-client": "^4.8.1",
     "web-vitals": "^2.1.4"
   },