提取编辑器历史上限常量

为撤销历史容量 100 增加命名常量，便于理解和调节内存权衡

apps/ai-game-creator-shell/src/features/ui-editor/useUiEditorState.ts

@@ -33,6 +33,8 @@ export const EMPTY_UI_EDITOR_STATE: State = {
   font_assets: {},
 };
 
+const MAX_HISTORY_LENGTH = 100;
+
 export type UiEditorOperationFailureReason =
   | 'locked'
   | 'duplicate'
@@ -567,7 +569,7 @@ export function useUiEditorState(initialState: State = EMPTY_UI_EDITOR_STATE) {
         before: cloneState(current),
         after: cloneState(nextState),
       });
-      if (undoStackRef.current.length > 100) {
+      if (undoStackRef.current.length > MAX_HISTORY_LENGTH) {
         undoStackRef.current.shift();
       }
       redoStackRef.current = [];