style: 精简顶栏，仅保留 logo，并微调首页卡片内边距

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/src/components/Topbar.vue

@@ -1,27 +1,9 @@
 <script setup>
-import { computed } from 'vue'
-import { useAppStore } from '@/stores/app'
 import logoUrl from '@/assets/logo.png'
-
-const store = useAppStore()
-const displayName = computed(() => store.currentUser?.name || '未登录')
-const avatarInitial = computed(() => (displayName.value || '?')[0].toUpperCase())
 </script>
 
 <template>
   <header class="topbar">
     <img class="topbar-logo" :src="logoUrl" alt="中国建筑材料科学研究总院有限公司" />
-    <div class="top-actions">
-      <span class="status-pill" :class="{ muted: !store.healthy }">
-        <span class="status-dot"></span>
-        {{ store.healthy ? '已连接' : '未连接' }}
-      </span>
-      <button class="topbar-icon" type="button" title="通知">🔔</button>
-      <div class="topbar-user">
-        <div class="topbar-user-avatar">{{ avatarInitial }}</div>
-        <span class="topbar-user-name">{{ displayName }}</span>
-        <span class="topbar-user-caret">▾</span>
-      </div>
-    </div>
   </header>
 </template>

frontend/src/styles/main.css

@@ -312,7 +312,7 @@ button {
 .topbar {
   display: flex;
   align-items: center;
-  justify-content: space-between;
+  justify-content: flex-end;
   gap: 16px;
   padding: 0 24px;
   background: transparent;
@@ -478,7 +478,7 @@ button {
   grid-template-columns: 1fr auto;
   gap: 24px;
   align-items: center;
-  padding: 24px 28px;
+  padding: 10px;
   border-radius: 14px;
   background:
     radial-gradient(circle at 90% 50%, #ffd1d4 0%, transparent 60%),