Media Attachments Now Use Media Category Code as Folder

Overview

Media attachments now use the Media Category code as the folder in the file URL in admin.

When a category code is set, uploads and links resolve to /uploads/{category_code}/{filename}. When the category code is empty, files stay under /uploads, and the admin stores only the filename while building the full URL from the category code at render time.

The media category help article has been updated to describe the new URL behavior.