fix(scene): never answer GetMapRotationData with an empty ScRsp

Client session 02:20 died in AdventurePhase._EnterStep1_InitializeMapInfo
('AdventureModule should not be null' -> RuntimeGroupManager
_InitMissionToLegacyGroupRelation NRE) and never left the loading screen.

The 01:00 session reached the scene when this request was dropped; the
empty reply added in the auto-empty round put the client into map-rotation
mode with a null state. Drop it again until real RotaterData is built.

internal/gameserver/handlers_ui.go

@@ -39,11 +39,10 @@ func init() {
 		return nil
 	})
 
-	// Amphoreus map rotation (teleport pillars) — empty but valid
-	handle("GetMapRotationData", func(s *Session, req *goproto.GetMapRotationDataCsReq, rsp *goproto.GetMapRotationDataScRsp) error {
-		rsp.Retcode = 0
-		return nil
-	})
+	// NOTE: GetMapRotationData (6827) must NOT be answered with an empty
+	// ScRsp - the client enters map-rotation mode with a null state and NREs
+	// in AdventurePhase._EnterStep1_InitializeMapInfo (no scene load).
+	// Implement real RotaterData before answering this one.
 
 	handle("GetPamSkinData", func(s *Session, req *goproto.GetPamSkinDataCsReq, rsp *goproto.GetPamSkinDataScRsp) error {
 		rsp.Retcode = 0