feat(staff): action buttons → filtered customer/group list

Adds groups.user_id filter; viewCustomers/viewGroups push owner_account_id query; CustomerList/GroupList read it.

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

yunkes/src/api/index.ts

@@ -134,6 +134,7 @@ export function getAccounts(query: AccountQuery = {}): Promise<Page<Account>> {
 export interface GroupQuery {
   channel?: Channel | 'all'
   owner_account_id?: string
+  user_id?: string
   page?: number
   page_size?: number
 }
@@ -144,6 +145,7 @@ export function getGroups(query: GroupQuery = {}): Promise<Page<Group>> {
     clean({
       channel: query.channel === 'all' ? undefined : query.channel,
       owner_account_id: query.owner_account_id,
+      user_id: query.user_id,
       page: query.page ?? 1,
       page_size: query.page_size ?? 20,
     }),