chore(backlog): 记录 g58 完成

.ua/backlog.json

@@ -820,6 +820,14 @@
       "acceptance": "FormRule.validator 允许返回 Promise；formItem 返回 validateAsync 并按轮次丢弃过期结论；form 提交逐项 await、期间禁用提交按钮、有错聚焦首错；同步 validate 行为不变；demo 增异步字段；npm run check 全绿",
       "status": "done",
       "notes": "自补：既有组件增强；同步路径不被 Promise 拖慢，异步路径防乱序覆盖"
+    },
+    {
+      "id": "g58",
+      "title": "新增 affix 固钉组件",
+      "motivation": "文档站目录、工具栏、筛选条都需要「滚过就贴顶」；直接用 position:sticky 常受父级 overflow 影响，需要占位 + fixed 的可靠实现",
+      "acceptance": "新增 affix(props, ...children)（阈值固定、外层等高占位不塌陷、宽度横向随容器自适应、支持内滚容器 target）；manifest/docs/demo/README/计数同步；npm run check 全绿",
+      "status": "done",
+      "notes": "自补：组件补充；固定态只在状态切换时重写样式，滚动中仅刷新宽度"
     }
   ]
 }

.ua/iterations.log

@@ -102,3 +102,4 @@
 {"ts":"2026-10-26T12:19:23+08:00","id":"g55","result":"done","commit":"e54fdb6","summary":"新增 checkboxGroup：数组信号+min/max 禁用边界+checkAll 半选+纵横向，组件数 53→54"}
 {"ts":"2026-10-26T12:20:34+08:00","id":"g56","result":"done","commit":"e6bf801","summary":"ua style 新增单文件 200 行门禁（分层包 src 实现文件，types/index 豁免），CODING 约定变可执行检查"}
 {"ts":"2026-10-26T12:22:13+08:00","id":"g57","result":"done","commit":"fcec391","summary":"form 校验支持异步规则：validator 可返回 Promise，formItem 新增 validateAsync 并按轮次丢弃过期结论，提交期间禁用按钮"}
+{"ts":"2026-10-26T12:23:29+08:00","id":"g58","result":"done","commit":"7684ae2","summary":"新增 affix 固钉：阈值转 fixed + 外层等高占位防塌陷 + 宽度横向自适应，组件数 54→55"}