feat(frontend): collapsible payment submenu in sidebar

Group the 4 payment admin pages under a single "订单管理" parent menu
item that expands/collapses to show sub-items with indented tree line.

frontend/src/components/layout/AppSidebar.vue

@@ -29,30 +29,64 @@
       <template v-if="isAdmin">
         <!-- Admin Section -->
         <div class="sidebar-section">
-          <router-link
-            v-for="item in adminNavItems"
-            :key="item.path"
-            :to="item.path"
-            class="sidebar-link mb-1"
-            :class="{ 'sidebar-link-active': isActive(item.path) }"
-            :title="sidebarCollapsed ? item.label : undefined"
-            :id="
-              item.path === '/admin/accounts'
-                ? 'sidebar-channel-manage'
-                : item.path === '/admin/groups'
-                  ? 'sidebar-group-manage'
-                  : item.path === '/admin/redeem'
-                    ? 'sidebar-wallet'
-                    : undefined
-            "
-            @click="handleMenuItemClick(item.path)"
-          >
-            <span v-if="item.iconSvg" class="h-5 w-5 flex-shrink-0 sidebar-svg-icon" v-html="sanitizeSvg(item.iconSvg)"></span>
-            <component v-else :is="item.icon" class="h-5 w-5 flex-shrink-0" />
-            <transition name="fade">
-              <span v-if="!sidebarCollapsed">{{ item.label }}</span>
-            </transition>
-          </router-link>
+          <template v-for="item in adminNavItems" :key="item.path">
+            <!-- Collapsible group (has children) -->
+            <template v-if="item.children?.length">
+              <button
+                type="button"
+                class="sidebar-link mb-1 w-full"
+                :class="{ 'sidebar-link-active': isGroupActive(item) && !isGroupExpanded(item) }"
+                :title="sidebarCollapsed ? item.label : undefined"
+                @click="sidebarCollapsed ? undefined : toggleGroup(item)"
+              >
+                <component :is="item.icon" class="h-5 w-5 flex-shrink-0" />
+                <transition name="fade">
+                  <span v-if="!sidebarCollapsed" class="flex flex-1 items-center justify-between">
+                    <span>{{ item.label }}</span>
+                    <ChevronDownIcon class="h-4 w-4 flex-shrink-0 transition-transform duration-200" :class="isGroupExpanded(item) ? 'rotate-180' : ''" />
+                  </span>
+                </transition>
+              </button>
+              <!-- Children -->
+              <div v-if="!sidebarCollapsed && isGroupExpanded(item)" class="mb-1 ml-4 border-l border-gray-200 pl-2 dark:border-dark-600">
+                <router-link
+                  v-for="child in item.children"
+                  :key="child.path"
+                  :to="child.path"
+                  class="sidebar-link mb-0.5 py-1.5 text-sm"
+                  :class="{ 'sidebar-link-active': route.path === child.path }"
+                  @click="handleMenuItemClick(child.path)"
+                >
+                  <component :is="child.icon" class="h-4 w-4 flex-shrink-0" />
+                  <span>{{ child.label }}</span>
+                </router-link>
+              </div>
+            </template>
+            <!-- Normal item (no children) -->
+            <router-link
+              v-else
+              :to="item.path"
+              class="sidebar-link mb-1"
+              :class="{ 'sidebar-link-active': isActive(item.path) }"
+              :title="sidebarCollapsed ? item.label : undefined"
+              :id="
+                item.path === '/admin/accounts'
+                  ? 'sidebar-channel-manage'
+                  : item.path === '/admin/groups'
+                    ? 'sidebar-group-manage'
+                    : item.path === '/admin/redeem'
+                      ? 'sidebar-wallet'
+                      : undefined
+              "
+              @click="handleMenuItemClick(item.path)"
+            >
+              <span v-if="item.iconSvg" class="h-5 w-5 flex-shrink-0 sidebar-svg-icon" v-html="sanitizeSvg(item.iconSvg)"></span>
+              <component v-else :is="item.icon" class="h-5 w-5 flex-shrink-0" />
+              <transition name="fade">
+                <span v-if="!sidebarCollapsed">{{ item.label }}</span>
+              </transition>
+            </router-link>
+          </template>
         </div>
 
         <!-- Personal Section for Admin (hidden in simple mode) -->
@@ -160,6 +194,7 @@ interface NavItem {
   icon: unknown
   iconSvg?: string
   hideInSimpleMode?: boolean
+  children?: NavItem[]
 }
 
 const { t } = useI18n()
@@ -175,6 +210,9 @@ const mobileOpen = computed(() => appStore.mobileOpen)
 const isAdmin = computed(() => authStore.isAdmin)
 const isDark = ref(document.documentElement.classList.contains('dark'))
 
+// Track which parent nav groups are expanded
+const expandedGroups = ref<Set<string>>(new Set())
+
 // Site settings from appStore (cached, no flicker)
 const siteName = computed(() => appStore.siteName)
 const siteLogo = computed(() => appStore.siteLogo)
@@ -513,6 +551,21 @@ const ChevronDoubleRightIcon = {
     )
 }
 
+const ChevronDownIcon = {
+  render: () =>
+    h(
+      'svg',
+      { fill: 'none', viewBox: '0 0 24 24', stroke: 'currentColor', 'stroke-width': '1.5' },
+      [
+        h('path', {
+          'stroke-linecap': 'round',
+          'stroke-linejoin': 'round',
+          d: 'm19.5 8.25-7.5 7.5-7.5-7.5'
+        })
+      ]
+    )
+}
+
 // User navigation items (for regular users)
 const userNavItems = computed((): NavItem[] => {
   const items: NavItem[] = [
@@ -622,10 +675,18 @@ const adminNavItems = computed((): NavItem[] => {
     { path: '/admin/promo-codes', label: t('nav.promoCodes'), icon: GiftIcon, hideInSimpleMode: true },
     ...(adminSettingsStore.paymentEnabled
       ? [
-          { path: '/admin/orders/dashboard', label: t('nav.paymentDashboard'), icon: ChartIcon, hideInSimpleMode: true },
-          { path: '/admin/orders', label: t('nav.orderManagement'), icon: OrderIcon, hideInSimpleMode: true },
-          { path: '/admin/orders/config', label: t('nav.paymentConfig'), icon: CogIcon, hideInSimpleMode: true },
-          { path: '/admin/orders/plans', label: t('nav.paymentPlans'), icon: CreditCardIcon, hideInSimpleMode: true },
+          {
+            path: '/admin/orders',
+            label: t('nav.orderManagement'),
+            icon: OrderIcon,
+            hideInSimpleMode: true,
+            children: [
+              { path: '/admin/orders/dashboard', label: t('nav.paymentDashboard'), icon: ChartIcon },
+              { path: '/admin/orders', label: t('nav.orderManagement'), icon: OrderIcon },
+              { path: '/admin/orders/config', label: t('nav.paymentConfig'), icon: CogIcon },
+              { path: '/admin/orders/plans', label: t('nav.paymentPlans'), icon: CreditCardIcon },
+            ],
+          },
         ]
       : []),
     { path: '/admin/usage', label: t('nav.usage'), icon: ChartIcon }
@@ -689,6 +750,23 @@ function isActive(path: string): boolean {
   return route.path === path || route.path.startsWith(path + '/')
 }
 
+function isGroupActive(item: NavItem): boolean {
+  if (!item.children) return false
+  return item.children.some(child => route.path === child.path)
+}
+
+function isGroupExpanded(item: NavItem): boolean {
+  return expandedGroups.value.has(item.path) || isGroupActive(item)
+}
+
+function toggleGroup(item: NavItem) {
+  if (expandedGroups.value.has(item.path)) {
+    expandedGroups.value.delete(item.path)
+  } else {
+    expandedGroups.value.add(item.path)
+  }
+}
+
 // Initialize theme
 const savedTheme = localStorage.getItem('theme')
 if (