Changes:
- Added verifyAllPaymentsCompleted() helper in MenuHelper.h to check if the authenticated customer has completed all invoices.
- Integrated payment verification into CustomerMenu::selectService() to block new service bookings when pending payments exist.
- Integrated payment verification into CustomerMenu::selectComboPackage() to block new combo package bookings when invoices are incomplete.
- Implemented iteration over customer invoices to ensure only users with all payments marked as COMPLETED can proceed with new bookings.
- Added user-facing messages to inform customers when bookings are denied due to outstanding payments.
Related work items: #2116
Avinash Rajesh
05b9fc7962