feat(engine): scaffold runtime skeleton

Data/Engine/services/WebSocket/__init__.py

@@ -0,0 +1,17 @@
+"""WebSocket service stubs for the Borealis Engine runtime.
+
+Future stages will move Socket.IO namespaces and event handlers here. Stage 1
+only keeps a placeholder so the Engine bootstrapper can stub registration
+without touching legacy behaviour.
+"""
+from __future__ import annotations
+
+from flask_socketio import SocketIO
+
+from ...server import EngineContext
+
+
+def register_realtime(socket_server: SocketIO, context: EngineContext) -> None:
+    """Placeholder hook for Socket.IO namespace registration."""
+
+    context.logger.debug("Engine WebSocket services are not yet implemented.")