iter(g113): 吸顶容器支持贴底固定

.ua/index.json

@@ -1,6 +1,6 @@
 {
   "$schema": "ui-arch-registry-index/0.1",
-  "generatedAt": "2026-10-26T06:05:26.104Z",
+  "generatedAt": "2026-10-26T06:06:20.403Z",
   "repoRoot": ".",
   "packages": [
     {
@@ -2813,6 +2813,11 @@
                 "t": "number",
                 "d": "距视口顶部多少像素后转为固定；缺省 0"
               },
+              {
+                "n": "position",
+                "t": "'top' | 'bottom'",
+                "d": "固定边：贴顶放头部工具栏，贴底放底部操作条；缺省 top"
+              },
               {
                 "n": "target",
                 "t": "HTMLElement | Window",
@@ -2829,7 +2834,8 @@
               "把要贴住的内容作为实参传入；组件内部包两层：外层占位、内层负责 fixed",
               "滚动到 offset 以内（默认贴视口顶）时内层转 fixed，外层同步撑出等高占位，页面不会塌跳",
               "固定期间宽度与横向位置跟随占位容器，窗口缩放或父容器变宽都自动贴合",
-              "内滚容器场景把该元素传给 target，判定改为基于它的滚动位置"
+              "内滚容器场景把该元素传给 target，判定改为基于它的滚动位置",
+              "底部操作条传 position: 'bottom'：占位容器底边越过「视口底 - offset」时才固定，对应的内联边距写 bottom"
             ]
           },
           {