feat: UI revamp with modern components and smooth animations

- Migrated to latest UI components (@primer/react, framer-motion, radix-ui)
- Implemented smooth animations and page transitions
- Added theme-aware components with light/dark mode support
- Created new leaderboard table with improved UX
- Added community stats dashboard with responsive grid layout
- Implemented pending PRs section with modern card design

API Changes:
- Using GitHub public REST API (no authentication required)
- PRs section now retrieves only PRs from the past 1 year
- Rate limit: 60 requests/hour per IP (unauthenticated)
- Excludes dependabot PRs automatically

Limitations:
- Backend changes not fully implemented in leaderboard-api
- Frontend directly calls GitHub public API for PRs
- Some backend endpoints may require GitHub token configuration

Note: PR section filters show only open PRs created within the past year from sliit-foss organization.

Author: moaalk

package.json

@@ -17,10 +17,18 @@
     "@fortawesome/react-fontawesome": "^0.2.2",
     "@primer/octicons-react": "^19.12.0",
     "@primer/react": "^37.31.0",
+    "@radix-ui/react-tooltip": "^1.0.7",
+    "@radix-ui/react-dropdown-menu": "^2.0.6",
+    "@radix-ui/react-tabs": "^1.0.4",
     "@tanstack/react-query": "^5.90.2",
     "axios": "^1.7.9",
+    "clsx": "^2.1.0",
+    "date-fns": "^3.3.1",
+    "framer-motion": "^11.0.0",
     "react": "^18.3.1",
     "react-dom": "^18.3.1",
+    "react-hot-toast": "^2.4.1",
+    "react-intersection-observer": "^9.10.3",
     "react-router-dom": "^6.28.0",
     "react-toggle": "^4.1.3",
     "recharts": "^2.15.0",