Track removal of the deprecated WP_SQLite_Driver API

[JanJakes]

Context

WP_MySQL_On_SQLite is now the primary PDO-compatible API, but the deprecated WP_SQLite_Driver class remains temporarily for backward compatibility.

Remove the compatibility class only after maintained dependent projects no longer instantiate, extend, type against, or otherwise depend on WP_SQLite_Driver or its legacy constructor and result API.

Known dependent projects

• WordPress/sqlite-database-integration production consumers (WordPress integration and MySQL proxy) use WP_MySQL_On_SQLite directly after Simplify the MySQL-on-SQLite driver API #449.
• Automattic/wp-cli-sqlite-command — tracked in Automattic/wp-cli-sqlite-command#34.
• WordPress/reprint — the exporter detects and wraps WP_SQLite_Driver.
• WordPress/desktop-mode — the phpMyAdmin SQLite adapter constructs WP_SQLite_Driver.
• WordPress/wordpress-playground — the PHP 5.2 compatibility patch references and modifies WP_SQLite_Driver.
• Automattic/markdown-database-integration — WP_Markdown_Driver extends WP_SQLite_Driver, and the write engine type-hints it.
• lucatume/wp-browser — its vendored SQLite integration constructs and branches on WP_SQLite_Driver.
• Inventory non-public/internal consumers, including WordPress Studio integrations.
• TODO: Add other known maintained dependent projects.

Public code search also finds many repositories containing vendored plugin copies or application snapshots. Re-run the search before removal, but do not treat every copied release as a separately coordinated dependency.

Removal criteria

• Every maintained dependent project above has migrated away from WP_SQLite_Driver.
• Re-run public GitHub code search and internal code search for WP_SQLite_Driver; classify any remaining maintained consumers.
• Decide and communicate the removal release and migration window.
• Remove class-wp-sqlite-driver.php, its loader entry, and compatibility-only tests.
• Update API documentation, migration guidance, and release notes.
• Run the full SQLite driver, WordPress integration, MySQL proxy, and relevant downstream test suites without the compatibility class.

[chubes4]

Markdown Database Integration migration is tracked in Automattic/markdown-database-integration#148 and implemented in Automattic/markdown-database-integration#150. It migrates production code and smoke doubles from the deprecated WP_SQLite_Driver compatibility API to WP_MySQL_On_SQLite/PDOStatement contracts, removes compatibility-class reflection, and documents the #449 API transition.