Import Tripoli Cloud frontend prototype

React/TypeScript/Vite/Tailwind prototype from the design session (login,
dashboard, photos, backups, settings views with mocked API layer).
Infra work (Rust services, Ansible, OpenTofu) follows in subsequent commits.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/src/components/layout/DrawerOverlay.tsx

@@ -0,0 +1,17 @@
+import { useNavigation } from '../../contexts/NavigationContext';
+import { useIsMobile } from '../../hooks/useIsMobile';
+
+export function DrawerOverlay() {
+  const { drawerOpen, closeDrawer } = useNavigation();
+  const isMobile = useIsMobile();
+
+  if (!isMobile || !drawerOpen) return null;
+
+  return (
+    <div
+      onClick={closeDrawer}
+      className="fixed inset-0 z-30 bg-black/60 backdrop-blur-sm"
+      aria-hidden="true"
+    />
+  );
+}