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

.env.example

@@ -0,0 +1,45 @@
+# CouncilOS — Environment Variables Template
+# Copy this file to .env and fill in your actual values.
+# NEVER commit the .env file to version control.
+
+# =============================================================================
+# LLM API Keys
+# =============================================================================
+
+# Anthropic Claude API key (required)
+ANTHROPIC_API_KEY=
+
+# OpenAI GPT-4o API key (optional for Phase 1, required from Phase 3)
+OPENAI_API_KEY=
+
+# Tavily Search API key (required for Phase 4 web-search tool)
+TAVILY_API_KEY=
+
+# =============================================================================
+# Database
+# =============================================================================
+
+# PostgreSQL connection string (required from Phase 2)
+DATABASE_URL=postgresql+asyncpg://user:password@localhost:5432/councilOS
+
+# =============================================================================
+# Vector Database (ChromaDB)
+# =============================================================================
+
+# Local directory to persist ChromaDB embeddings (required for Phase 4 PDF tool)
+CHROMA_PERSIST_DIR=./chroma_db
+
+# =============================================================================
+# Application Settings
+# =============================================================================
+
+# FastAPI server host and port
+HOST=0.0.0.0
+PORT=8000
+
+# Log level: DEBUG | INFO | WARNING | ERROR
+LOG_LEVEL=INFO
+
+# CORS: comma-separated list of allowed frontend origins in production
+# Example: https://my-app.vercel.app,https://www.my-domain.com
+CORS_ORIGINS=http://localhost:3000