Fix SSE CORS headers for credentialed streaming endpoints

backend/api/content_planning/api/content_strategy/endpoints/streaming_endpoints.py

@@ -124,10 +124,6 @@ async def stream_enhanced_strategies(
         headers={
             "Cache-Control": "no-cache",
             "Connection": "keep-alive",
-            "Access-Control-Allow-Origin": "*",
-            "Access-Control-Allow-Headers": "*",
-            "Access-Control-Allow-Methods": "GET, POST, OPTIONS",
-            "Access-Control-Allow-Credentials": "true"
         }
     )
 
@@ -261,10 +257,6 @@ async def stream_strategic_intelligence(
         headers={
             "Cache-Control": "no-cache",
             "Connection": "keep-alive",
-            "Access-Control-Allow-Origin": "*",
-            "Access-Control-Allow-Headers": "*",
-            "Access-Control-Allow-Methods": "GET, POST, OPTIONS",
-            "Access-Control-Allow-Credentials": "true"
         }
     )