feat: add sidebar layout, environment tree, and router

Wires up AppShell + Sidebar compound component, a per-environment
SidebarTree that lazy-fetches apps, React Router nested routes, and
provider-wrapped main.tsx with ThemeProvider/ToastProvider/BreadcrumbProvider.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ui/src/router.tsx

@@ -0,0 +1,39 @@
+import { Routes, Route } from 'react-router';
+import { useEffect } from 'react';
+import { useAuthStore } from './auth/auth-store';
+import { LoginPage } from './auth/LoginPage';
+import { CallbackPage } from './auth/CallbackPage';
+import { ProtectedRoute } from './auth/ProtectedRoute';
+import { Layout } from './components/Layout';
+import { DashboardPage } from './pages/DashboardPage';
+import { EnvironmentsPage } from './pages/EnvironmentsPage';
+import { EnvironmentDetailPage } from './pages/EnvironmentDetailPage';
+import { AppDetailPage } from './pages/AppDetailPage';
+import { LicensePage } from './pages/LicensePage';
+
+export function AppRouter() {
+  const loadFromStorage = useAuthStore((s) => s.loadFromStorage);
+  useEffect(() => {
+    loadFromStorage();
+  }, [loadFromStorage]);
+
+  return (
+    <Routes>
+      <Route path="/login" element={<LoginPage />} />
+      <Route path="/callback" element={<CallbackPage />} />
+      <Route
+        element={
+          <ProtectedRoute>
+            <Layout />
+          </ProtectedRoute>
+        }
+      >
+        <Route index element={<DashboardPage />} />
+        <Route path="environments" element={<EnvironmentsPage />} />
+        <Route path="environments/:envId" element={<EnvironmentDetailPage />} />
+        <Route path="environments/:envId/apps/:appId" element={<AppDetailPage />} />
+        <Route path="license" element={<LicensePage />} />
+      </Route>
+    </Routes>
+  );
+}