feat(FN-005): implement frontend foundation with auth and routing

- Add OIDC authentication with PKCE flow
- Create dashboard shell with sidebar and header
- Implement project management UI (list, create, detail)
- Add tool spawn page with tool/project selection
- Create tool instance detail page with status and controls
- Set up React Router with route guards
- Add Zustand auth store and API client with types

apps/web/src/components/RouteGuard.tsx

@@ -0,0 +1,20 @@
+import { Navigate } from 'react-router-dom'
+import { useAuthStore } from '../stores/auth'
+
+export default function RouteGuard({ children }: { children: React.ReactNode }) {
+  const { state } = useAuthStore()
+
+  if (state === 'loading') {
+    return (
+      <div className="flex min-h-screen items-center justify-center">
+        <div className="animate-spin rounded-full h-8 w-8 border-b-2 border-accent"></div>
+      </div>
+    )
+  }
+
+  if (state === 'unauthenticated' || state === 'error') {
+    return <Navigate to="/login" replace />
+  }
+
+  return <>{children}</>
+}