Phase 1: auth, room CRUD, WebSocket chat, PWA frontend

Invite-only FastAPI + SQLAlchemy(async) + Postgres backend (session-cookie
auth via CLI-provisioned accounts, open-room CRUD, single-instance /ws/chat)
and a React + Vite PWA frontend (login, room list, chat view). Backend tests
pass against a local Postgres DB. See README.md and backend/README.md for
setup, and ARCHITECTURE.md for the full phased design.

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

frontend/src/components/ProtectedRoute.tsx

@@ -0,0 +1,12 @@
+import type { ReactNode } from 'react'
+import { Navigate } from 'react-router-dom'
+import { useAuth } from '../context/AuthContext'
+
+export function ProtectedRoute({ children }: { children: ReactNode }) {
+  const { user, loading } = useAuth()
+
+  if (loading) return <p>Loading...</p>
+  if (!user) return <Navigate to="/login" replace />
+
+  return <>{children}</>
+}