Bundled library: webklex/php-imap 4.1.2

Why this copy exists
- WP Mailster is not Composer-driven at runtime, so this library is bundled as ready-to-use assets.
- This copy is intended to support a future alternative mailbox backend for PHP 7 / PHP 8 environments.

Local security backport
- Upstream advisory: GHSA-47p7-xfcc-4pv9 / CVE-2023-35169
- Upstream fixed release: webklex/php-imap 5.3.0
- The bundled 4.1.2 copy includes a local backport of the Attachment::save() filename sanitization fix.
- Patched file:
  vendor/webklex/php-imap/src/Attachment.php

Important note
- Composer/audit tools may still report version 4.1.2 as vulnerable because they only see the package version.
- The local backport is in the source tree, but it does not change upstream package metadata.

If this library is updated or rebuilt
- Re-check the upstream security status.
- Re-apply or verify the local Attachment.php backport if staying on 4.x.
- Prefer replacing this note with an upstream-fixed version if a suitable PHP 7/8 compatible release becomes available.