feat(admin): add optional ID column on groups list

Add a toggleable group ID column in /admin/groups column settings.
It shows the group id (e.g. #1), is hidden by default for new and
existing admins via column-settings version migration, and remains
sortable against the existing backend sort_by=id support.

frontend/src/i18n/locales/en/admin/overview.ts

@@ -757,6 +757,7 @@ export default {
       public: 'Public',
       columns: {
         name: 'Name',
+        id: 'ID',
         platform: 'Platform',
         rateMultiplier: 'Rate Multiplier',
         rpmOverride: 'RPM Override',

frontend/src/i18n/locales/zh/admin/overview.ts

@@ -750,6 +750,7 @@ export default {
         "确定要删除订阅分组 '{name}' 吗？此操作会让所有绑定此订阅的用户的 API Key 失效，并删除所有相关的订阅记录。此操作无法撤销。",
       columns: {
         name: '名称',
+        id: 'ID',
         platform: '平台',
         rateMultiplier: '费率倍数',
         rpmOverride: 'RPM 覆盖',