feat: home page with MUI components

- Rewrote frontend from JSX to TypeScript (TSX)
- AppLayout with MUI AppBar, ThemeProvider, CssBaseline
- HomePage at / with dashboard metrics and recent updates
- MetricsPanel with 4 metric cards (total, interviews, offers, rejection rate)
- UpdateCard for each job update with status chip
- LoadingSkeleton during data fetch
- Error Alert on API failure
- Create New Job Application button navigating to /applications/new
- Vite proxy for /api → backend on :8000
- useDashboardData custom hook with concurrent fetch

Closes #2

web/package.json

@@ -5,15 +5,23 @@
   "type": "module",
   "scripts": {
     "dev": "vite",
-    "build": "vite build",
+    "build": "tsc -b && vite build",
     "preview": "vite preview"
   },
   "dependencies": {
+    "@emotion/react": "^11.14.0",
+    "@emotion/styled": "^11.14.0",
+    "@mui/icons-material": "^7.0.0",
+    "@mui/material": "^7.0.0",
     "react": "^19.0.0",
-    "react-dom": "^19.0.0"
+    "react-dom": "^19.0.0",
+    "react-router-dom": "^7.0.0"
   },
   "devDependencies": {
+    "@types/react": "^19.0.0",
+    "@types/react-dom": "^19.0.0",
     "@vitejs/plugin-react": "^4.3.0",
+    "typescript": "^5.7.0",
     "vite": "^6.0.0"
   }
-}
+}