feat(frontend): improve admin usability and light theme

frontend/platform_admin/src/views/dashboard/DashboardPage.vue

@@ -1,6 +1,11 @@
 <template>
   <div class="dashboard">
     <a-spin :loading="loading" class="dashboard-spin">
+      <a-alert v-if="errorMessage" type="error" show-icon class="dashboard-alert">
+        {{ errorMessage }}
+        <template #action><a-button size="small" @click="loadOverview">重新加载</a-button></template>
+      </a-alert>
+      <div class="dashboard-meta">统计口径以服务端为准 · 更新时间：{{ updatedAt || '尚未加载' }}</div>
       <a-grid :cols="{ xs: 1, sm: 2, lg: 4 }" :col-gap="16" :row-gap="16">
         <a-grid-item v-for="item in cards" :key="item.key">
           <a-card :bordered="false" class="metric-card">
@@ -58,6 +63,8 @@ const emptyOverview = (): DashboardOverview => ({
   order_statuses: [], product_statuses: [], payment_channels: [], recent_orders: [],
 });
 const loading = ref(false);
+const errorMessage = ref('');
+const updatedAt = ref('');
 const overview = ref<DashboardOverview>(emptyOverview());
 const router = useRouter();
 const userStore = useUserStore();
@@ -110,8 +117,9 @@ const paymentChannelOption = computed<EChartsOption>(() => ({
   series: [{ type: 'bar', data: safeArray(overview.value.payment_channels).map((item) => centsToYuan(item.value)) }],
 }));
 
-onMounted(async () => {
+async function loadOverview() {
   loading.value = true;
+  errorMessage.value = '';
   try {
     const data = await platformApi.overview();
     overview.value = {
@@ -124,17 +132,23 @@ onMounted(async () => {
       payment_channels: safeArray(data.payment_channels),
       recent_orders: safeArray(data.recent_orders),
     };
+    updatedAt.value = new Date().toLocaleString('zh-CN', { hour12: false });
   } catch (error) {
-    Message.error((error as Error).message);
+    errorMessage.value = (error as Error).message;
+    Message.error(errorMessage.value);
   } finally {
     loading.value = false;
   }
-});
+}
+
+onMounted(loadOverview);
 </script>
 
 <style scoped lang="less">
 .dashboard { padding: 20px; }
 .dashboard-spin { width: 100%; }
+.dashboard-alert { margin-bottom: 16px; }
+.dashboard-meta { margin-bottom: 12px; color: var(--color-text-3); font-size: 12px; text-align: right; }
 .metric-card { min-height: 120px; }
 .metric-hint { margin-top: 8px; color: var(--color-text-3); font-size: 12px; }
 .section-card { margin-top: 16px; }