feat(degree): /degree/favorite accept-only (persistence deferred)

SVSim.EmulatedEntrypoint/Controllers/DegreeController.cs

@@ -38,4 +38,14 @@ public class DegreeController : SVSimController
                 .ToList(),
         };
     }
+
+    [HttpPost("favorite")]
+    public ActionResult<EmptyResponse> Favorite([FromBody] DegreeFavoriteRequest _)
+    {
+        if (!TryGetViewerId(out long __)) return Unauthorized();
+        // Accept-and-ack. Persisting per-viewer cosmetic favorites is deferred until
+        // a viewer-favorites schema lands (would also serve /sleeve/favorite + /emblem/favorite
+        // via the shared Wizard/FavoriteTask.cs Kind enum).
+        return new EmptyResponse();
+    }
 }