feat: WS request proxy — Gateway proxies HTTP via WebSocket (#210 Phase 2)

- Add ws-protocol.ts with WsRequest/WsResponse types + parsers
- AgentSocket DO: proxy POST handler, pending request map, 30s timeout
- /api/agents/:agent/* routes through DO WS when connected, falls back to HTTP
- ws-client handles incoming WsRequest, fetches local serve, returns WsResponse
- startGatewayWsClient accepts localPort for request handling

Testing: #213

packages/cli-workflow/package.json

@@ -6,6 +6,7 @@
     "uncaged-workflow": "src/cli.ts"
   },
   "dependencies": {
+    "@uncaged/workflow-gateway": "workspace:*",
     "@uncaged/workflow-protocol": "workspace:*",
     "@uncaged/workflow-util": "workspace:*",
     "@uncaged/workflow-cas": "workspace:*",