Replace the single-listener createWebSocket pattern with a pub/sub model
using addListener/removeListener. This allows multiple components (header
spinner, dashboard refresh) to subscribe to WebSocket messages independently
without clobbering each other's handlers.
- Maintain a Set of message listeners
- Auto-connect on first addListener, auto-disconnect when last listener removed
- Retain reconnect logic with configurable delay
john-okeefe
d61abb1be1