feat(teams): fix checkbox multi-select and improve batch operations UI

- Fix checkbox binding using :model-value instead of :checked
- Change selectedIds from Set to reactive array for proper Vue reactivity
- Move batch refresh/delete buttons to top bar (matching CardKeysPage layout)
- Buttons show selection count like 'Refresh (2)' when items selected
- Swap position of 'Add Team' and 'Random Invite' buttons
- Remove unused isIndeterminate computed property

backend/internal/repository/invitation_repo.go

@@ -82,6 +82,12 @@ func (r *InvitationRepository) DeleteByEmailAndAccountID(email string, accountID
 	return err
 }
 
+// DeleteByAccountID 根据账号ID删除所有邀请记录
+func (r *InvitationRepository) DeleteByAccountID(accountID int) error {
+	_, err := r.db.Exec(`DELETE FROM invitations WHERE account_id = $1`, accountID)
+	return err
+}
+
 // FindByAccountID 根据账号ID查找邀请记录
 func (r *InvitationRepository) FindByAccountID(accountID int) ([]*models.Invitation, error) {
 	rows, err := r.db.Query(`