iter: e02 新增 stepper 步骤条组件（三态流转 + active 信号双向绑定 + clickable 回跳）

.ua/backlog.json

@@ -284,6 +284,14 @@
       "acceptance": "packages/skin/ui 新增 inputNumber.ts：−/+ 按钮 + 输入框三段式，value 信号双向绑定，min/max/step 超界自动夹取，键盘 ↑↓ 调节，非法输入回滚，disabled 支持布尔或信号；只消费 --ua-* 令牌；导出、manifest、文档、llms-full.txt 同步；demo 加一节演示；npm run check 全绿",
       "status": "done",
       "notes": "inputNumber(props)：−/+ 复用 ghost button（自带微动画与 disabled 透传），输入框 inputmode=decimal，change 时 parseFloat 解析、非法回滚当前值；↑↓ 步进并 preventDefault；clamp 统一夹取 min/max（缺省 ±Infinity）；aria-label 三件套 + role=group；CSS 步进按钮收窄、tabular-nums；demo 新增 sec-inputnumber（与禁用态实例共用 qty 信号）；manifest/docs/llms-full/README 同步为 29 组件"
+    },
+    {
+      "id": "e02",
+      "title": "新增 stepper 步骤条组件",
+      "motivation": "下单、注册等多步流程需要进度指示与回跳，现有导航类组件（tabs/breadcrumb/pagination）都不覆盖分步语义；纯展示 + 可选点击回跳，改动范围可控",
+      "acceptance": "packages/skin/ui 新增 stepper.ts：stepper({steps, active, clickable?, onChange?})，done/current/upcoming 三态视觉，clickable 时已完成步骤可点回跳并写回 active 信号，aria-current=step；只消费 --ua-* 令牌；导出、manifest、文档、llms-full.txt、README 清单同步；demo 加一节演示；npm run check 全绿",
+      "status": "done",
+      "notes": "stepper(props)：active 信号变化整条重渲染（effect 首跑赋值 + replaceWith，条目少开销可忽略）；done 显示 ✓、current 光环聚焦、upcoming 弱化，aria-current=step；clickable 时已完成步骤渲染为 button 回跳写回信号；连接线用 .ua-step + .ua-step::before 横向短线；demo 新增 sec-stepper（上一步/下一步按钮 computed 禁用联动）；README 同步 30 组件"
     }
   ]
 }

.ua/index.json

@@ -1,6 +1,6 @@
 {
   "$schema": "ui-arch-registry-index/0.1",
-  "generatedAt": "2026-10-23T09:49:54.480Z",
+  "generatedAt": "2026-10-23T09:57:15.241Z",
   "repoRoot": ".",
   "packages": [
     {
@@ -167,6 +167,7 @@
           "spinner(props)：加载指示器，size 控制直径",
           "progress(props)：进度条，value 信号驱动 0-100（满格切 success 色）；不传 value 退化为不确定态无限往复",
           "tabs(props)：标签页，active 信号双向绑定，滑动指示条 + 方向键环形导航，支持禁用页签",
+          "stepper(props)：步骤条，done/current/upcoming 三态，active 信号双向绑定，clickable 时已完成步骤可回跳",
           "modal(props, ...children)：弹窗，open 信号驱动显隐，Esc / 遮罩 / × 关闭，size 三档宽度，footer 提供底部操作区",
           "drawer(props, ...children)：抽屉，open 信号驱动侧滑面板，placement 左右可配、width 可调、footer 操作区，遮罩 / × / Esc 关闭",
           "form(props, items)：表单容器，布局 + 聚合校验，全部通过才触发 onSubmit",
@@ -1107,6 +1108,42 @@
               "键盘可访问：Tab 聚焦激活页签，←→ 在启用页签间环形移动"
             ]
           },
+          {
+            "id": "stepper",
+            "title": "步骤条 Stepper",
+            "demo": "sec-stepper",
+            "props": [
+              {
+                "n": "steps",
+                "t": "StepperItem[]",
+                "r": 1,
+                "d": "步骤列表，每项 { label, description? }"
+              },
+              {
+                "n": "active",
+                "t": "Signal<number>",
+                "r": 1,
+                "d": "当前步索引（0 基）信号，双向绑定：回跳写回、外部赋值同步"
+              },
+              {
+                "n": "clickable",
+                "t": "boolean",
+                "d": "已完成步骤是否可点击回跳；缺省 false"
+              },
+              {
+                "n": "onChange",
+                "t": "(index: number) => void",
+                "k": 1,
+                "d": "步骤切换回调（点击回跳触发）"
+              }
+            ],
+            "example": "const step = signal(1); stepper({ steps: [{ label: '下单' }, { label: '支付' }, { label: '完成' }], active: step, clickable: true })",
+            "steps": [
+              "用 signal(0) 创建当前步索引，传入 active；索引之前的步骤显示 ✓ 已完成态",
+              "流程推进时外部赋值即可：step(step() + 1)，组件三态自动跟随",
+              "clickable: true 时已完成步骤可点击回跳并写回信号，配合 onChange 同步业务状态"
+            ]
+          },
           {
             "id": "pagination",
             "title": "分页器 Pagination",

.ua/iterations.log

@@ -35,3 +35,4 @@
 {"ts": "2026-10-23T09:11:42+00:00", "round": 28, "id": "d28", "result": "done", "commit": "", "summary": "drawer 焦点陷阱对齐 modal"}
 {"ts": "2026-10-23T09:12:49+00:00", "round": 29, "id": "d29", "result": "done", "commit": "", "summary": "menu Home/End 跳转对齐 select"}
 {"ts":"2026-10-23T17:50:14+08:00","id":"e01","result":"done","commit":"20d7b94","summary":"新增 inputNumber 数字输入：−/+ 按钮 + 键盘上下步进，信号双向绑定，min/max/step 夹取，门禁全绿"}
+{"ts":"2026-10-23T17:57:31+08:00","id":"e02","result":"done","commit":"pending","summary":"新增 stepper 步骤条：三态流转 + active 信号双向绑定 + clickable 回跳，门禁全绿"}