feat(admin): /admin/users 新增按用户 API Key 所在分组过滤

- 支持专用/公开/订阅/已禁用四类分组：按 api_keys.group_id 精确匹配，
  排除软删除 key（EXISTS + DeletedAtIsNil）；已禁用分组单独成区，
  覆盖 key 仍挂在禁用分组上的用户
- 后端：UserListFilters.APIKeyGroupID；handler 解析 api_key_group_id；
  repo HasAPIKeysWith 谓词；GetAllGroupsIncludingInactive 新接口
  (/admin/groups/all?include_inactive=true)
- 前端：下拉按类型分区单选；UsersView 独立 allGroupsForApiKeyFilter
  loader；分区标题用负数哨兵值修复 Vue :key 重复问题
- 测试：repo 集成 5/5（含软删除排除、多 key 去重、叠加 status 过滤）、
  handler 单测 5/5、前端 vitest 6/6

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/api/admin/groups.ts

@@ -57,6 +57,17 @@ export async function getAll(platform?: GroupPlatform): Promise<AdminGroup[]> {
   return data
 }
 
+/**
+ * Get ALL groups including disabled ones — used by the API Key group filter so
+ * that admins can filter users whose keys are still bound to a now-disabled group.
+ */
+export async function getAllIncludingInactive(): Promise<AdminGroup[]> {
+  const { data } = await apiClient.get<AdminGroup[]>('/admin/groups/all', {
+    params: { include_inactive: true }
+  })
+  return data
+}
+
 /**
  * Get active groups by platform
  * @param platform - Platform to filter by
@@ -322,6 +333,7 @@ export const groupsAPI = {
   list,
   getAll,
   getByPlatform,
+  getAllIncludingInactive,
   getById,
   getModelsListCandidates,
   create,

frontend/src/api/admin/users.ts

@@ -60,6 +60,7 @@ export async function list(
     role?: 'admin' | 'user'
     search?: string
     group_name?: string         // fuzzy filter by allowed group name
+    api_key_group_id?: number   // filter users by the group their API keys are bound to
     attributes?: Record<number, string>  // attributeId -> value
     include_subscriptions?: boolean
     sort_by?: string
@@ -77,6 +78,7 @@ export async function list(
     role: filters?.role,
     search: filters?.search,
     group_name: filters?.group_name,
+    api_key_group_id: filters?.api_key_group_id,
     include_subscriptions: filters?.include_subscriptions,
     sort_by: filters?.sort_by,
     sort_order: filters?.sort_order