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/App.tsx

@@ -0,0 +1,49 @@
+import { AuthLayout } from './components/auth/AuthLayout';
+import { AppShell } from './components/layout/AppShell';
+import { BackupsView } from './components/backups/BackupsView';
+import { DashboardView } from './components/dashboard/DashboardView';
+import { PhotosView } from './components/photos/PhotosView';
+import { SettingsView } from './components/settings/SettingsView';
+import { NavigationProvider, useNavigation } from './contexts/NavigationContext';
+import { SessionProvider, useSession } from './contexts/SessionContext';
+import { ThemeProvider } from './contexts/ThemeContext';
+
+/** Content router — a plain state switch (NavigationContext.nav), no react-router. */
+function AppContent() {
+  const { nav } = useNavigation();
+
+  switch (nav) {
+    case 'dashboard':
+      return <DashboardView />;
+    case 'photos':
+      return <PhotosView />;
+    case 'backups':
+      return <BackupsView />;
+    case 'settings':
+      return <SettingsView />;
+  }
+}
+
+function Root() {
+  const { view } = useSession();
+
+  if (view === 'auth') return <AuthLayout />;
+
+  return (
+    <NavigationProvider>
+      <AppShell>
+        <AppContent />
+      </AppShell>
+    </NavigationProvider>
+  );
+}
+
+export default function App() {
+  return (
+    <ThemeProvider>
+      <SessionProvider>
+        <Root />
+      </SessionProvider>
+    </ThemeProvider>
+  );
+}