feat(admin): Add group filtering for account listings

- Add groupID parameter to ListAccounts and ListWithFilters methods
- Implement account filtering by group ID in repository query
- Add group query parameter parsing in account handler
- Update all ListAccounts/ListWithFilters call sites with groupID parameter
- Add group filter UI component to AccountTableFilters
- Add i18n translations for group filter label in English and Chinese
- Update API contract and test stubs to reflect new signature
- Enable filtering accounts by their assigned groups in admin panel

backend/internal/handler/admin/account_data.go

@@ -341,7 +341,7 @@ func (h *AccountHandler) listAccountsFiltered(ctx context.Context, platform, acc
 	pageSize := dataPageCap
 	var out []service.Account
 	for {
-		items, total, err := h.adminService.ListAccounts(ctx, page, pageSize, platform, accountType, status, search)
+		items, total, err := h.adminService.ListAccounts(ctx, page, pageSize, platform, accountType, status, search, 0)
 		if err != nil {
 			return nil, err
 		}