The picker accepts one MP4 or WebM, the thread lightbox zooms photos, and Discord gets the video as a file on a follow-up message so photo embeds still render.
Handlers emit PostCreated and PostUpdated after a successful write. Store writes do not publish, and hidden roots are skipped.
Reviewed-on: #13
Co-authored-by: codegirl-007 <s.raide@gmail.com>
codegirl007