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/project/urls.py

@@ -1,4 +1,7 @@
 from django.contrib import admin
-from django.urls import path
+from django.urls import include, path
 
-urlpatterns: list = []
+urlpatterns = [
+    path("admin/", admin.site.urls),
+    path("api/", include("jobs.urls")),
+]