MySQL-on-SQLite lacks geo query function compatibility

Bug

The current MySQL-on-SQLite driver cannot execute common MySQL geo expressions combining RADIANS(), COS(), SIN(), and SUBSTRING_INDEX() over a comma-separated coordinate value. WP Codebox calendar PHPUnit cases reach these queries but the compatibility layer reports database errors instead of translating or providing the functions.

Representative expression:

RADIANS(CAST(SUBSTRING_INDEX(meta_value, ',', 1) AS DECIMAL(10,7)))

Runtime

• WordPress Playground / WP Codebox
• WordPress 7.0.2
• PHP 8.3.31
• SQLite integration path: wp-includes/database/sqlite/class-wp-pdo-mysql-on-sqlite.php

Expected

Provide compatibility for these MySQL scalar functions, or document a compatibility-layer primitive for registering them in test runtimes.

Impact

This blocks geo-filter assertions in Extra-Chill/data-machine-events CalendarAbilitiesTest under the SQLite-backed WP Codebox runtime.

Start in wp-includes/database/sqlite/class-wp-pdo-mysql-on-sqlite.php and inspect how SQLite compatibility functions are registered. Reproduce the failing geo queries through the WP Codebox CalendarAbilitiesTest cases, then verify that RADIANS(), COS(), SIN(), and SUBSTRING_INDEX() execute successfully without database errors.