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/jobs/admin.py

@@ -0,0 +1,17 @@
+from django.contrib import admin
+
+from .models import JobApplication, JobUpdate
+
+
+@admin.register(JobApplication)
+class JobApplicationAdmin(admin.ModelAdmin):
+    list_display = ["company_name", "position_title", "status", "created_at", "updated_at"]
+    list_filter = ["status"]
+    search_fields = ["company_name", "position_title"]
+
+
+@admin.register(JobUpdate)
+class JobUpdateAdmin(admin.ModelAdmin):
+    list_display = ["job_application", "from_status", "to_status", "created_at"]
+    list_filter = ["to_status"]
+    search_fields = ["job_application__company_name"]