PHP 8.2 compatibility update - 07 Oct 2026

Checks performed:
- Full PHP syntax scan across 1,512 PHP files.
- Legacy ext/mysql compatibility layer verified (mysqli-backed wrappers retained to preserve application behaviour).
- Fixed PHPExcel dynamic property deprecation affecting PHP 8.2.
- Fixed PHPExcel OLE continue/switch warning.
- Replaced deprecated PHPExcel strftime() date-component calls with date().
- Removed invalid/redundant final modifier from private WxPay notification methods.
- Re-scanned all PHP files after changes.
- Basic PHPExcel and WxPay class loading smoke tests completed.

Important deployment requirements:
- PHP 8.2 with mysqli enabled.
- Keep the existing database and site files backed up before replacing production files.
- Live payment callbacks, database writes, email/SMS, and external APIs cannot be fully integration-tested offline; test these functions on staging after upload.