Video aspect ratio setting is ignored

Problem/Motivation

The existing Ratio setting has no effect because the module passes it as plyr.ratio, while the GLightbox library expects plyr.config.ratio. This affects both explicitly configured ratios and leaving the setting blank for automatic sizing.

Steps to reproduce

1. Go to /admin/config/media/glightbox.
2. Set Ratio to 4:3, save and clear caches.
3. Open a video in GLightbox.

Expected: the configured ratio is used. Actual: the setting is ignored and the library retains its default configuration.

Proposed resolution

Correct the configuration path in GLightboxAttachment::attach(). Add a Kernel regression test covering blank, landscape and portrait settings.

Remaining tasks

Review the merge request.

User interface changes

The existing Ratio setting works as described. No new settings.

API changes

The attached JavaScript setting moves from plyr.ratio to plyr.config.ratio.

Data model changes

None.

AI-Generated: Yes (Used Codex to help investigate and prepare the change.)