RELEASE

** Key changes in this version:**

Removed the add_image_to_library method entirely.
Modified the set_featured_image_by_url method:

1. If the image is already in the media library, it sets it as the featured image.
2. If the image is not in the media library, it stores the URL as post meta.
3. Added an external_thumbnail_html method to display external images as featured images.
   Updated the URL metabox to display the current external URL if set.

This version of the plugin will:

Set the first image in a post as the featured image if it's already in the media library.
For external images not in the media library, store the URL and display it as the featured image without adding it to the library.
Provide a meta box to manually set or update the featured image URL.