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/ws/useChatSocket.ts

@@ -0,0 +1,52 @@
+import { useCallback, useEffect, useRef, useState } from 'react'
+import type { ServerEnvelope } from '../types'
+
+interface UseChatSocketOptions {
+  roomId: string
+  onMessage: (envelope: ServerEnvelope) => void
+  onUnauthenticated: () => void
+}
+
+export function useChatSocket({ roomId, onMessage, onUnauthenticated }: UseChatSocketOptions) {
+  const socketRef = useRef<WebSocket | null>(null)
+  const [connected, setConnected] = useState(false)
+  const onMessageRef = useRef(onMessage)
+  onMessageRef.current = onMessage
+  const onUnauthenticatedRef = useRef(onUnauthenticated)
+  onUnauthenticatedRef.current = onUnauthenticated
+
+  useEffect(() => {
+    const protocol = location.protocol === 'https:' ? 'wss' : 'ws'
+    const ws = new WebSocket(`${protocol}://${location.host}/ws/chat`)
+    socketRef.current = ws
+
+    ws.onopen = () => {
+      setConnected(true)
+      ws.send(JSON.stringify({ type: 'join', room_id: roomId }))
+    }
+
+    ws.onmessage = (event) => {
+      onMessageRef.current(JSON.parse(event.data) as ServerEnvelope)
+    }
+
+    ws.onclose = (event) => {
+      setConnected(false)
+      if (event.code === 4401) {
+        onUnauthenticatedRef.current()
+      }
+    }
+
+    return () => {
+      ws.close()
+      socketRef.current = null
+    }
+  }, [roomId])
+
+  const send = useCallback((content: string) => {
+    const ws = socketRef.current
+    if (!ws || ws.readyState !== WebSocket.OPEN) return
+    ws.send(JSON.stringify({ type: 'message', room_id: roomId, content }))
+  }, [roomId])
+
+  return { connected, send }
+}