Scaffold @forte/admin package with React, Vite, shadcn/ui, TanStack Router

Sets up the admin frontend with login page, auth guard, API client, Zustand
auth store, and all shadcn/ui components. Vite proxies /v1 to backend in dev.

packages/admin/src/main.tsx

@@ -0,0 +1,23 @@
+import { StrictMode } from 'react'
+import { createRoot } from 'react-dom/client'
+import { RouterProvider, createRouter } from '@tanstack/react-router'
+import { QueryClientProvider } from '@tanstack/react-query'
+import { queryClient } from '@/lib/query-client'
+import { routeTree } from './routeTree.gen'
+import './app.css'
+
+const router = createRouter({ routeTree })
+
+declare module '@tanstack/react-router' {
+  interface Register {
+    router: typeof router
+  }
+}
+
+createRoot(document.getElementById('root')!).render(
+  <StrictMode>
+    <QueryClientProvider client={queryClient}>
+      <RouterProvider router={router} />
+    </QueryClientProvider>
+  </StrictMode>,
+)