Fix stream_with_context usage: it's a decorator, not a wrapper

stream_with_context decorates a generator function, not a generator
instance. Wrap execute_page_streaming in a decorated inner function.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

shared/sx/pages.py

@@ -520,10 +520,15 @@ def _mount_one_page(bp: Any, service_name: str, page_def: PageDef) -> None:
                 if hasattr(result, "status_code"):
                     return result
                 return await make_response(result, 200)
-            # Streaming response — stream_with_context preserves app/request
-            # context across async generator yields
-            gen = execute_page_streaming(current, service_name, url_params=kwargs)
-            return Response(stream_with_context(gen), content_type="text/html; charset=utf-8")
+            # stream_with_context is a decorator — wrap the generator function
+            # so app/request context is preserved across yields
+            @stream_with_context
+            async def _stream():
+                async for chunk in execute_page_streaming(
+                    current, service_name, url_params=kwargs,
+                ):
+                    yield chunk
+            return Response(_stream(), content_type="text/html; charset=utf-8")
     else:
         # Standard non-streaming response
         async def page_view(**kwargs: Any) -> Any: