implement bop for expedition must recheck and qty in staff purchase need info

internal/modules/expenses/services/number_helper.go

@@ -0,0 +1,17 @@
+package service
+
+import (
+	"context"
+	"fmt"
+
+	expenseRepo "gitlab.com/mbugroup/lti-api.git/internal/modules/expenses/repositories"
+)
+
+// GenerateExpenseReferenceNumber builds a new reference number using the expense sequence.
+func GenerateExpenseReferenceNumber(ctx context.Context, repo expenseRepo.ExpenseRepository) (string, error) {
+	sequence, err := repo.GetNextSequence(ctx)
+	if err != nil {
+		return "", err
+	}
+	return fmt.Sprintf("BOP-LTI-%05d", sequence), nil
+}