feat: complete phase 5 -- error hardening, frontend, Docker, demo, docs

Backend:
- ConversationTracker: Protocol + PostgresConversationTracker for lifecycle tracking
- Error handler: ErrorCategory enum, classify_error(), with_retry() exponential backoff
- Wire PostgresAnalyticsRecorder + ConversationTracker into ws_handler
- Rate limiting (10 msg/10s per thread), edge case hardening
- Health endpoint GET /api/health, version 0.5.0
- Demo seed data script + sample OpenAPI spec

Frontend (all new):
- React Router with NavBar (Chat / Replay / Dashboard / Review)
- ReplayListPage + ReplayPage with ReplayTimeline component
- DashboardPage with MetricCard, range selector, zero-state
- ReviewPage for OpenAPI classification review
- ErrorBanner for WebSocket disconnect handling
- API client (api.ts) with typed fetch wrappers

Infrastructure:
- Frontend Dockerfile (multi-stage node -> nginx)
- nginx.conf with SPA routing + API/WS proxy
- docker-compose.yml with frontend service + healthchecks
- .env.example files (root + backend)

Documentation:
- README.md with quick start and architecture
- Agent configuration guide
- OpenAPI import guide
- Deployment guide
- Demo script

48 new tests, 449 total passing, 92.87% coverage

docs/deployment.md

@@ -0,0 +1,152 @@
+# Deployment Guide
+
+## Docker Compose (Recommended)
+
+### Prerequisites
+
+- Docker Engine 24+
+- Docker Compose v2
+
+### Quick Start
+
+```bash
+git clone <repo-url>
+cd smart-support
+
+# Configure environment
+cp .env.example .env
+# Edit .env: set ANTHROPIC_API_KEY (or OPENAI_API_KEY / GOOGLE_API_KEY)
+
+# Start all services
+docker compose up -d
+
+# Verify health
+docker compose ps
+curl http://localhost/api/health
+```
+
+The app is available at http://localhost (frontend) and http://localhost:8000 (backend API).
+
+### Services
+
+| Service | Port | Description |
+|---------|------|-------------|
+| postgres | 5432 | PostgreSQL 16 database |
+| backend | 8000 | FastAPI + LangGraph backend |
+| frontend | 80 | React SPA served by nginx |
+
+### Stopping
+
+```bash
+docker compose down          # Stop services, keep data
+docker compose down -v       # Stop services and delete database volume
+```
+
+## Production Considerations
+
+### Environment Variables
+
+Set these in production (never commit secrets):
+
+| Variable | Required | Description |
+|----------|----------|-------------|
+| `POSTGRES_PASSWORD` | Yes | Strong random password |
+| `ANTHROPIC_API_KEY` | Yes* | LLM provider API key |
+| `LLM_PROVIDER` | Yes | `anthropic`, `openai`, or `google` |
+| `LLM_MODEL` | Yes | Model name for your provider |
+| `WEBHOOK_URL` | No | Escalation notification endpoint |
+| `SESSION_TTL_MINUTES` | No | Session timeout (default: 30) |
+
+*Or `OPENAI_API_KEY` / `GOOGLE_API_KEY` depending on `LLM_PROVIDER`.
+
+### HTTPS
+
+For production, place a reverse proxy (nginx, Caddy, or a load balancer) in
+front of the frontend container and configure TLS termination there.
+
+The WebSocket endpoint at `/ws` must be proxied with `Upgrade: websocket` headers.
+The frontend nginx.conf handles this internally for the backend connection.
+
+Example Caddy configuration:
+
+```
+example.com {
+    reverse_proxy localhost:80
+}
+```
+
+### Database Backups
+
+```bash
+# Backup
+docker compose exec postgres pg_dump -U smart_support smart_support > backup.sql
+
+# Restore
+cat backup.sql | docker compose exec -T postgres psql -U smart_support smart_support
+```
+
+### Scaling
+
+The backend is stateless (session state is in PostgreSQL via LangGraph's
+PostgresSaver). You can run multiple backend replicas behind a load balancer.
+
+The WebSocket connections are session-specific. Use sticky sessions or a shared
+session backend if load balancing WebSockets across multiple instances.
+
+## Manual / Development Setup
+
+### Backend
+
+```bash
+cd backend
+python -m venv .venv
+source .venv/bin/activate   # Windows: .venv\Scripts\activate
+pip install -e ".[dev]"
+
+# Set environment variables
+cp .env.example .env
+# Edit .env
+
+# Start database
+docker compose up postgres -d
+
+# Run backend
+uvicorn app.main:app --host 0.0.0.0 --port 8000 --reload
+```
+
+### Frontend
+
+```bash
+cd frontend
+npm install
+npm run dev    # Dev server on http://localhost:5173
+```
+
+### Running Tests
+
+```bash
+cd backend
+pytest --cov=app --cov-report=term-missing
+```
+
+## Health Checks
+
+### Backend health
+
+```http
+GET /api/health
+```
+
+Response:
+```json
+{"status": "ok", "version": "0.5.0"}
+```
+
+### WebSocket health
+
+Connect to `ws://localhost:8000/ws` and send:
+```json
+{"type": "message", "thread_id": "health-check", "content": "ping"}
+```
+
+A `message_complete` or `error` response confirms the WebSocket is alive.