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

api/pyproject.toml

@@ -5,9 +5,11 @@ description = "Job Tracker API"
 requires-python = ">=3.12"
 dependencies = [
     "django>=5.1,<6.0",
+    "django-cors-headers>=4.9.0",
+    "djangorestframework>=3.17.1",
     "psycopg2-binary>=2.9",
 ]
 
 [build-system]
 requires = ["setuptools"]
-build-backend = "setuptools.build_meta"
+build-backend = "setuptools.build_meta"