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/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",