- Implemented WHMCS invoice creation and payment capture in SimManagementService for top-ups.
- Updated top-up logic to calculate costs based on GB input, with pricing set at 500 JPY per GB.
- Simplified the Top Up Modal interface, removing unnecessary fields and improving user experience.
- Added new methods in WhmcsService for invoice and payment operations.
- Enhanced error handling for payment failures and added transaction logging for audit purposes.
- Updated documentation to reflect changes in the SIM management flow and API interactions.
- Introduced `validateSignup` endpoint in AuthController for customer number validation during signup.
- Added `healthCheck` method in AuthService to verify service integrations and database connectivity.
- Implemented `getPaymentMethods`, `getPaymentGateways`, and `refreshPaymentMethods` endpoints in InvoicesController for managing user payment options.
- Enhanced InvoicesService with methods to invalidate payment methods cache and improved error handling.
- Updated currency handling across various services and components to reflect JPY as the default currency.
- Added new dependencies in package.json for ESLint configuration.
