Add tests verifying that the broadcast case in Hub.Run() correctly
sends messages only to clients in the same room as the sender:
- TestIntegration_RoomIsolation_MessagesOnlyGoToSameRoom: verifies
messages from room-a are received by room-a clients and NOT by
room-b clients
- TestIntegration_RoomIsolation_MultipleRoomsIndependent: verifies
two rooms operate independently with no message leakage
- TestIntegration_BroadcastToEmptyRoom: verifies graceful handling
when broadcasting to a non-existent room (no panic, hub remains
functional)
- TestBroadcastRoomIsolation: unit-level room isolation test using
the broadcast channel directly
Also adds dialWSWithRoom helper for room-aware WebSocket connections
in integration tests.
🤖 Assisted by the code-assist SOP
48d47dfc92