修复 Unity 编译：EnumMetadata using + nullable 警告

src/Unity/Assets/Scripts/Managers/ScenarioManager.cs

@@ -49,7 +49,7 @@ namespace CounterDrone.Unity
         public void DeleteScenario(string id) => _service.DeleteScenario(id);
         public Scenario UpdateScenario(Scenario s) => _service.UpdateScenario(s);
         public ScenarioConfig GetDetail(string id) => _service.GetScenarioDetail(id);
-        public PagedResult<Scenario> Search(string kw, string? from, string? to, int page, int size)
+        public PagedResult<Scenario> Search(string kw, string from, string to, int page, int size)
             => _service.SearchScenarios(kw, from, to, page, size);
 
         public void SaveScene(string scenarioId, CombatScene s) => _service.SaveScene(scenarioId, s);