BirchPress Scheduler Business 2.8.25.B - compatibility patch notes

This is a preliminary compatibility patch for newer PHP versions.

Changes made:
- Replaced removed curly-brace string-offset syntax in bundled calendar code.
- Parenthesized a nested ternary expression that PHP 8 rejects.
- Renamed the bundled Sabre VObject Property\Float class to Property\FloatValue because Float is reserved by PHP, and updated the class mappings.

Validation performed:
- PHP syntax lint passed for all 297 PHP files under PHP 8.4.24.
- Confirmed the renamed Sabre VObject class can be autoloaded.

Important limitations:
- This patch has not been tested against a live WordPress 7.1.3 site or a PHP 8.3 runtime.
- It has not been functionally tested for bookings, payments, email, calendar export/import, upgrades, or third-party integrations.
- Back up the site and database and test on a staging copy before installing on a production site.
