Implement Phase 1: LangGraph backend MVP

Sets up the full backend foundation for CouncilOS:

- CouncilState TypedDict with all required fields and LangGraph reducers
- Three agent nodes: master_agent (drafts), critic_agent (scores + routes),
  writer_agent (final polish)
- LangGraph graph with cyclic rework loop: Master → Critic → (score < 8:
  back to Master | score ≥ 8: Writer → END)
- Safety valve: MAX_ITERATIONS=5 prevents infinite loops
- FastAPI app with REST endpoints (POST /api/councils/run, GET /api/councils/run/{id})
  and WebSocket endpoint (/ws/council/{run_id}) for real-time agent status events
- In-memory RunStore for Phase 1 (PostgreSQL-backed in Phase 3)
- pytest test suite: state, routing logic, critic parser, agent nodes, API endpoints
- .env.example, .gitignore, docker-compose.yml, Dockerfile

https://claude.ai/code/session_01RfMpt3TbMjZEtK3CAyP5iQ

.gitignore

@@ -0,0 +1,72 @@
+# =============================================================================
+# Environment & Secrets — NEVER commit these
+# =============================================================================
+.env
+.env.local
+.env.*.local
+*.pem
+*.key
+secrets/
+
+# =============================================================================
+# Python
+# =============================================================================
+__pycache__/
+*.py[cod]
+*$py.class
+*.so
+.Python
+.venv/
+venv/
+env/
+ENV/
+*.egg-info/
+dist/
+build/
+.eggs/
+pip-wheel-metadata/
+.mypy_cache/
+.ruff_cache/
+.pytest_cache/
+htmlcov/
+.coverage
+coverage.xml
+*.cover
+
+# =============================================================================
+# Node / Frontend
+# =============================================================================
+node_modules/
+.next/
+out/
+.nuxt/
+dist/
+.cache/
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+.pnpm-debug.log*
+
+# =============================================================================
+# Database & Vector Store
+# =============================================================================
+chroma_db/
+*.sqlite3
+*.db
+postgres_data/
+
+# =============================================================================
+# IDE & OS
+# =============================================================================
+.idea/
+.vscode/
+*.swp
+*.swo
+.DS_Store
+Thumbs.db
+
+# =============================================================================
+# Docker
+# =============================================================================
+.docker/