fix(miniprogram): unify nav headers to dashboard style with tall workbench bar

Co-authored-by: Cursor <cursoragent@cursor.com>

miniprogram/pages/common/biz-placeholder.vue

@@ -23,12 +23,14 @@ const goBack = () => {
 
 <template>
   <view class="mp-page">
-    <view class="mp-header" :style="safeAreaStyle">
-      <view class="biz-placeholder__nav" @click="goBack">
-        <text class="biz-placeholder__back">← 工作台</text>
+    <view class="sq-nav-header" :style="safeAreaStyle">
+      <view class="sq-nav-header__nav">
+        <view class="sq-nav-header__left">
+          <text class="sq-nav-header__back" @click="goBack">←</text>
+          <text class="sq-nav-header__title">{{ title }}</text>
+        </view>
+        <view /><!-- 胶囊占位 -->
       </view>
-      <text class="mp-header__title" style="margin-top: 16rpx">{{ title }}</text>
-      <text v-if="moduleTitle" class="mp-header__meta">{{ moduleTitle }}</text>
     </view>
     <view class="mp-placeholder">
       <view class="mp-placeholder__icon" />
@@ -36,26 +38,16 @@ const goBack = () => {
       <text class="mp-placeholder__desc">
         P0 壳层已就绪，业务列表/详情将在后续阶段（P1–P4）实现。
       </text>
+      <text v-if="moduleTitle" class="biz-placeholder__code">{{ moduleTitle }}</text>
       <text v-if="code" class="biz-placeholder__code">菜单编码：{{ code }}</text>
     </view>
   </view>
 </template>
 
 <style lang="scss" scoped>
-.biz-placeholder__nav {
-  min-height: 44rpx;
-}
-
-.biz-placeholder__back {
-  color: #fff;
-  font-size: 26rpx;
-  opacity: 0.95;
-}
-
 .biz-placeholder__code {
-  display: block;
-  margin-top: 12rpx;
+  margin-top: 16rpx;
   font-size: 22rpx;
-  color: #9aa8a1;
+  color: #94a3b8;
 }
 </style>