[mdabubakkarhq]

Added

• Added a gateway setting that selects SSLCommerz's current conversion rate or the configured WHMCS rate for non-BDT invoices.

Changed

• Locked the original invoice amount and gateway processing amount separately for callback validation, reconciliation, and refunds.
• Documented that checkout converts the current outstanding invoice balance without adding a module-level surcharge or convenience fee.
• Updated the gateway configuration documentation and screenshot for the new conversion setting.