fix(ui): 修复单行对话框未激活时空引用

Co-authored-by: Cursor <cursoragent@cursor.com>

Assets/Scripts/UI/DialogUI/OnelineBox.cs

@@ -39,10 +39,13 @@ namespace AibisDream
             syncToken.SkipTextAnima += () => content.SkipTypewriter();
             syncToken.OnAdvance += AfterAdvance;
 
+            // TMP ClearMesh 依赖 canvasRenderer；box 未激活时 SetText 会 NRE
+            if (box != null && !box.activeSelf)
+                box.SetActive(true);
+
             // 播放文字
             content.TextAnimator.SetText(string.Empty);
             var lineText = GetOneLineText(syncToken.lineInfo);
-            box.SetActive(true);
             HandleLayout(lineText);
             content.ShowText(lineText);
             syncToken.TextStart();