同步入口移至首页：MarketSyncBar 手动同步A股当日数据并展示最新更新日期；选股页移除数据状态条与同步逻辑

frontend/src/views/HomeView.vue

@@ -2,6 +2,7 @@
 import { RouterLink } from 'vue-router';
 
 import MarketOverview from '@/components/MarketOverview.vue';
+import MarketSyncBar from '@/components/MarketSyncBar.vue';
 
 // 首页：大盘行情总览 + 三大功能入口（看股 / 选股 / 回测）
 const features = [
@@ -33,6 +34,8 @@ const features = [
   <div class="w-full max-w-5xl">
     <MarketOverview />
 
+    <MarketSyncBar />
+
     <div class="grid gap-6 sm:grid-cols-2 lg:grid-cols-3">
       <RouterLink
         v-for="f in features"