feat: 自有餐品库改名+终端管理重构为分组菜单

- 自由餐品库 → 自有餐品库，路径 din-dish-free.html → din-dish-own.html
- 「终端管理」升级为可展开二级菜单组，下设「设备管理」(din-terminal.html) 和「内容中心」(din-content-center.html 新增)
- 同步更新全部营养用餐分组页面侧边栏及 index.html SITE_MAP

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

index.html

@@ -294,14 +294,15 @@ const SITE_MAP = [
       { file:'sup-clean-external.html', label:'净菜外售' },
       { file:'din-user-mgmt.html', label:'用户管理' },
       { file:'din-dish-all.html', label:'菜品总库' },
-      { file:'din-dish-free.html', label:'自由餐品库' },
+      { file:'din-dish-own.html', label:'自有餐品库' },
       { file:'din-dish-all-dialog.html', label:'菜品总库弹窗', dialog:true },
       { file:'din-dish-add.html', label:'新增菜品' },
       { file:'din-ingredient.html', label:'食材管理' },
       { file:'din-ingredient-dialog.html', label:'食材管理弹窗', dialog:true },
       { file:'din-ingredient-detail.html', label:'食材详情' },
       { file:'din-recipe-mgmt.html', label:'食谱管理' },
-      { file:'din-terminal.html', label:'终端管理' },
+      { file:'din-terminal.html', label:'设备管理' },
+      { file:'din-content-center.html', label:'内容中心' },
       { file:'din-order-meal.html', label:'点餐订单' },
       { file:'din-order-line.html', label:'排队取餐' },
       { file:'din-order-pickup.html', label:'取餐管理' },