fix(gateway): implement proper OpenClaw WebSocket handshake protocol
- Send JSON-RPC connect request after WebSocket opens (required by OpenClaw Gateway)
- Use OpenClaw protocol format: { type: "req" } instead of { jsonrpc: "2.0" }
- Include proper ConnectParams: client info, auth token, protocol version
- Handle OpenClaw response format: { type: "res", ok: true/false }
- Handle OpenClaw event format: { type: "event", event: "..." }
- Wait for handshake completion before marking connection as running
- Improve error handling for connection failures
The Gateway was rejecting connections because:
1. ClawX wasn't sending the required "connect" handshake message
2. The protocol format was incorrect (standard JSON-RPC vs OpenClaw format)
