Revert "merge: tier2/phase2_4_5_call_site_completion_20260621 (parent + follow-up + Phase 6e analysis)"

This reverts commit f914b2bcd4, reversing
changes made to 7fef95cc87.

tests/test_websocket_server.py

@@ -2,7 +2,7 @@ import pytest
 import asyncio
 import json
 import websockets
-from src.api_hooks import WebSocketMessage, WebSocketServer
+from src.api_hooks import WebSocketServer
 
 @pytest.mark.asyncio
 async def test_websocket_subscription_and_broadcast():
@@ -32,7 +32,7 @@ async def test_websocket_subscription_and_broadcast():
    
    # Broadcast an event from the server
    event_payload = {"event": "test_event", "data": "hello"}
-   server.broadcast(WebSocketMessage(channel="events", payload=event_payload))
+   server.broadcast("events", event_payload)
    
    # Receive the broadcast
    broadcast_response = await websocket.recv()