refactor(auth): remove billing_id validation from transaction and invoice RPCs

Remove ensureBillingAccountBelongToOrg checks from authorization interceptors
for 4 RPCs:
- ListBillingTransactions
- TotalDebitedTransactions
- ListInvoices
- GetUpcomingInvoice

Since billing_id is now always inferred from org_id by handlers, the separate
validation that billing_id belongs to org_id is redundant.

Author: whoAbhishekSah

pkg/server/connect_interceptors/authorization.go

@@ -907,32 +907,20 @@ var authorizationValidationMap = map[string]func(ctx context.Context, handler *v
 	},
 	"/raystack.frontier.v1beta1.FrontierService/ListBillingTransactions": func(ctx context.Context, handler *v1beta1connect.ConnectHandler, req connect.AnyRequest) error {
 		pbReq := req.(*connect.Request[frontierv1beta1.ListBillingTransactionsRequest])
-		if err := ensureBillingAccountBelongToOrg(ctx, handler, pbReq.Msg.GetOrgId(), pbReq.Msg.GetBillingId()); err != nil {
-			return err
-		}
 		return handler.IsAuthorized(ctx, relation.Object{Namespace: schema.OrganizationNamespace, ID: pbReq.Msg.GetOrgId()}, schema.GetPermission, req)
 	},
 	"/raystack.frontier.v1beta1.FrontierService/TotalDebitedTransactions": func(ctx context.Context, handler *v1beta1connect.ConnectHandler, req connect.AnyRequest) error {
 		pbReq := req.(*connect.Request[frontierv1beta1.TotalDebitedTransactionsRequest])
-		if err := ensureBillingAccountBelongToOrg(ctx, handler, pbReq.Msg.GetOrgId(), pbReq.Msg.GetBillingId()); err != nil {
-			return err
-		}
 		return handler.IsAuthorized(ctx, relation.Object{Namespace: schema.OrganizationNamespace, ID: pbReq.Msg.GetOrgId()}, schema.GetPermission, req)
 	},
 
 	// invoice
 	"/raystack.frontier.v1beta1.FrontierService/ListInvoices": func(ctx context.Context, handler *v1beta1connect.ConnectHandler, req connect.AnyRequest) error {
 		pbReq := req.(*connect.Request[frontierv1beta1.ListInvoicesRequest])
-		if err := ensureBillingAccountBelongToOrg(ctx, handler, pbReq.Msg.GetOrgId(), pbReq.Msg.GetBillingId()); err != nil {
-			return err
-		}
 		return handler.IsAuthorized(ctx, relation.Object{Namespace: schema.OrganizationNamespace, ID: pbReq.Msg.GetOrgId()}, schema.UpdatePermission, req)
 	},
 	"/raystack.frontier.v1beta1.FrontierService/GetUpcomingInvoice": func(ctx context.Context, handler *v1beta1connect.ConnectHandler, req connect.AnyRequest) error {
 		pbReq := req.(*connect.Request[frontierv1beta1.GetUpcomingInvoiceRequest])
-		if err := ensureBillingAccountBelongToOrg(ctx, handler, pbReq.Msg.GetOrgId(), pbReq.Msg.GetBillingId()); err != nil {
-			return err
-		}
 		return handler.IsAuthorized(ctx, relation.Object{Namespace: schema.OrganizationNamespace, ID: pbReq.Msg.GetOrgId()}, schema.UpdatePermission, req)
 	},