Solver Quote Stream (WebSocket)

WebSocket endpoint for solvers to receive real-time RFQ broadcasts. Connect, authenticate, subscribe to channels, and receive events. **Connection flow:** 1. Connect to `wss://api.tetrafi.io/v1/ws/solver/stream` 2. Send auth: `{ "type": "auth", "token": "sk_live_..." }` 3. Subscribe: `{ "type": "subscribe", "channels": ["rfq.*"] }` 4. Receive RFQ events and submit quotes