Add landing page, referral system, usage quotas, search API management, and yearly pricing

- Separate workspace landing from login for better UX
- Referral system rewards both parties with Pro days
- Quota enforcement prevents abuse without breaking endpoints
- 7-day free trial with auto-downgrade on expiry
- Admin-managed search provider config (SearXNG, Bing)
- 15% discount on annual subscriptions
- MCP search server wrapping opencode search
- Fix discovery module field name mismatch causing 422

admin-frontend/src/layouts/AdminLayout.vue

@@ -2,8 +2,8 @@
   <el-container class="layout-container">
     <el-aside :width="collapsed ? '64px' : '220px'" class="sidebar">
       <div class="sidebar-header">
-        <span v-show="!collapsed" class="logo-text">TradeMate</span>
-        <span v-show="collapsed" class="logo-text logo-sm">TM</span>
+        <router-link v-show="!collapsed" to="/" class="logo-text">TradeMate</router-link>
+        <router-link v-show="collapsed" to="/" class="logo-text logo-sm">TM</router-link>
       </div>
       <el-menu
         :default-active="route.path"
@@ -42,6 +42,16 @@
           <el-icon><List /></el-icon>
           <span>发票管理</span>
         </el-menu-item>
+        <el-sub-menu index="/system">
+          <template #title>
+            <el-icon><Tools /></el-icon>
+            <span>系统管理</span>
+          </template>
+          <el-menu-item index="/system/search-config">
+            <el-icon><Search /></el-icon>
+            <span>搜索配置</span>
+          </el-menu-item>
+        </el-sub-menu>
       </el-menu>
     </el-aside>
 
@@ -99,7 +109,7 @@ const collapsed = ref(false)
 .layout-container { height: 100vh; }
 .sidebar { background: #fff; border-right: 1px solid #e8e8e8; transition: width 0.3s; overflow: hidden; }
 .sidebar-header { height: 60px; display: flex; align-items: center; justify-content: center; border-bottom: 1px solid #f0f0f0; }
-.logo-text { color: #1890ff; font-size: 18px; font-weight: 700; white-space: nowrap; }
+.logo-text { color: #1890ff; font-size: 18px; font-weight: 700; white-space: nowrap; text-decoration: none; }
 .logo-sm { font-size: 16px; }
 .sidebar :deep(.el-menu) { border-right: none; }
 .sidebar :deep(.el-menu-item) { margin: 2px 8px; border-radius: 8px; }