Fix async handling in router controller

Add await keyword before transformResponse call to properly handle the Promise
returned by the method. This resolves the issue where the router endpoint
returns empty objects instead of the expected content.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: cayblood

packages/core/server/controllers/core.ts

@@ -35,7 +35,7 @@ export default {
 
     // Format response.
     const sanitizedEntity = await sanitizeOutput(responseEntity, contentTypeObj, auth);
-    ctx.body = strapi.controller(contentType as UID.Controller)
+    ctx.body = await strapi.controller(contentType as UID.Controller)
       // @ts-expect-error
       // The strapi object is typed in a way that the following is expected to be a controller.
       // In fact that is not true, as this also exposes the helper functions of the controller.