Node-RED: WebSocket Server Nodes

Provides Node-RED nodes for running a WebSocket server with open/close event information. Version 0.0.9 wraps the built-in Node-RED WebSocket node and adds extra features: configurable ping/pong behavior (send ping, receive ping with timeout), ability to target specific clients via msg._session, and a dedicated node for connection open/close events. It is maintained on GitHub but has low release cadence. Key differentiators vs built-in: explicit control over ping, session-based messaging, and event nodes.