chore(backlog): 记录 g338 完成

.ua/backlog.json

@@ -3435,7 +3435,7 @@
       "title": "toast 通知读屏可达",
       "motivation": "toast 目前只走视觉通道，读屏用户完全感知不到通知的出现与消失",
       "acceptance": "toast 容器带 aria-live=polite，error 级别用 role=alert 抢占播报；audit 与 verify 全绿",
-      "status": "open",
+      "status": "done",
       "notes": ""
     }
   ]

.ua/iterations.log

@@ -382,3 +382,4 @@
 {"ts":"2026-10-27T02:09:25+08:00","id":"g335","result":"done","commit":"19d5e90","summary":"textField/textarea/inputNumber/slider 增 ariaLabel（缺省沿用通用名），区间滑块自动拼上下限；四份清单文档同步"}
 {"ts":"2026-10-27T02:10:09+08:00","id":"g336","result":"done","commit":"da09e29","summary":"全选框与行复选框补可访问名（选择第 N 行），选中行加 aria-selected；文件仍 198 行"}
 {"ts":"2026-10-27T02:13:15+08:00","id":"g337","result":"done","commit":"1d25c8a","summary":"新增可访问名门禁：verify 扫描 combobox/slider/range 控件，补齐 commandPalette 搜索框 aria-label"}
+{"ts":"2026-10-27T02:14:56+08:00","id":"g338","result":"done","commit":"28972a0","summary":"toast 容器补 aria-live=polite 兜底播报，error 级别 role=alert 抢占"}