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>

backend/middleware/validators/profileValidator.js

@@ -0,0 +1,52 @@
+const { body, validationResult } = require("express-validator");
+
+const URL_REGEX = /^(https?|ftp):\\/\\/[^\\s\\/$.?#].[^\\s]*$/i;
+
+const validateProfile = [
+  body("bio")
+    .optional()
+    .isLength({ max: 500 })
+    .withMessage("Bio cannot exceed 500 characters."),
+  body("location").optional().isString(),
+  body("website")
+    .optional()
+    .if(body("website").notEmpty())
+    .matches(URL_REGEX)
+    .withMessage("Invalid website URL."),
+  body("social.twitter")
+    .optional()
+    .if(body("social.twitter").notEmpty())
+    .matches(URL_REGEX)
+    .withMessage("Invalid Twitter URL."),
+  body("social.github")
+    .optional()
+    .if(body("social.github").notEmpty())
+    .matches(URL_REGEX)
+    .withMessage("Invalid Github URL."),
+  body("social.linkedin")
+    .optional()
+    .if(body("social.linkedin").notEmpty())
+    .matches(URL_REGEX)
+    .withMessage("Invalid LinkedIn URL."),
+  body("privacySettings.profileVisibility")
+    .optional()
+    .isIn(["public", "private"])
+    .withMessage("Profile visibility must be public or private."),
+  body("preferences.emailNotifications").optional().isBoolean(),
+  body("preferences.pushNotifications").optional().isBoolean(),
+  body("preferences.theme")
+    .optional()
+    .isIn(["light", "dark"])
+    .withMessage("Theme must be light or dark."),
+
+  (req, res, next) => {
+    const errors = validationResult(req);
+    if (!errors.isEmpty()) {
+      return res.status(400).json({ errors: errors.array() });
+    }
+    next();
+  },
+];
+
+module.exports = { validateProfile };
+