fix(test): add IncrementQuotaUsed to all APIKeyRepository test stubs

- Add missing IncrementQuotaUsed method to stubApiKeyRepo in api_contract_test.go
- Fix gofmt formatting issues in api_key_service.go, dto/types.go, api_key_handler.go

backend/internal/server/api_contract_test.go

@@ -1434,6 +1434,10 @@ func (r *stubApiKeyRepo) ListKeysByGroupID(ctx context.Context, groupID int64) (
 	return nil, errors.New("not implemented")
 }
 
+func (r *stubApiKeyRepo) IncrementQuotaUsed(ctx context.Context, id int64, amount float64) (float64, error) {
+	return 0, errors.New("not implemented")
+}
+
 type stubUsageLogRepo struct {
 	userLogs map[int64][]service.UsageLog
 }