Summary

• Bump plugin version 4.5.5 → 4.6.0
• Raise minimum required PHP version from 7.2 → 7.4 in composer.json (headers were already at 7.4)
• Add 4.6.0 changelog entry to readme.md

Changelog (4.6.0)

• Add FedCM (Federated Credential Management) support
• Fix critical error when client is not found in the taxonomy
• Raise minimum required PHP version to 7.4

Note: dependency bumps and dev-tooling changes since 4.5.5 (wp-env migration, PHPUnit/PHPCS setup, etc.) are intentionally omitted from the user-facing changelog. Tested up to: 7.0 is unchanged.