refactor: 在仪表板中添加加载横幅组件，提升用户体验

src/pages/dashboard.vue

@@ -1007,6 +1007,8 @@ onBeforeUnmount(() => {
 </script>
 
 <template>
+  <LoadingBanner v-if="!isDashboardRevealed" class="mt-12" />
+
   <!-- 仪表板 -->
   <div
     ref="dashboardGridRef"

src/styles/common.scss

@@ -142,7 +142,6 @@ html[data-theme-shadow='high'] {
 .v-sheet,
 .v-list,
 .v-expansion-panel {
-  border: var(--app-surface-border);
   border-radius: var(--app-surface-radius) !important;
   box-shadow: var(--app-surface-shadow) !important;
   transition: border-color 0.2s ease, border-radius 0.2s ease, box-shadow 0.2s ease;
@@ -275,6 +274,14 @@ html[data-theme-skin='bordered'] {
     border-block: 0;
     border-inline-start: 0;
   }
+
+  .app-surface,
+  .v-card,
+  .v-sheet,
+  .v-list,
+  .v-expansion-panel {
+    border: var(--app-surface-border);
+  }
 }
 
 // 应用类信息卡片：固定右侧媒体槽位，避免图片被左侧文字挤压变形。