feat: Complete frontend master upgrade with PWA, SEO, Bundle Analysis, and State Management

- Install nanostores for lightweight state management
- Add enhanced Directus client with auth and realtime
- Configure PWA with offline support and service worker
- Enable auto-sitemap generation for SEO
- Add Partytown for web worker analytics
- Implement image optimization with astro-imagetools
- Add bundle visualizer for performance analysis
- Enable Brotli compression for all assets
- Add Vite Inspect for debugging
- Create sidebar state management store
- Install TipTap rich text editor
- Add React Hook Form + Zod validation
- Add TanStack Query for data fetching

All plugins tested and build verified successfully.

frontend/src/stores/sidebarStore.ts

@@ -0,0 +1,17 @@
+import { atom } from 'nanostores';
+
+// Sidebar open/close state
+export const isSidebarOpen = atom(true);
+
+// Active route for highlighting
+export const activeRoute = atom('/admin');
+
+// Helper to toggle sidebar
+export function toggleSidebar() {
+    isSidebarOpen.set(!isSidebarOpen.get());
+}
+
+// Helper to set active route
+export function setActiveRoute(route: string) {
+    activeRoute.set(route);
+}