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>

.gitignore

@@ -0,0 +1,24 @@
+## Python
+__pycache__/
+*.pyc
+.venv/
+*.egg-info/
+
+## Env / secrets
+.env
+!.env.example
+
+## Node / frontend
+node_modules/
+dist/
+dist-ssr/
+*.local
+
+## Editors / OS
+.vscode/
+.idea/
+.DS_Store
+
+## Test / coverage
+.pytest_cache/
+.coverage