bt-linkding av ttscoff

A port of the linkding extension by Sascha Ißbrücker that opens the bookmark panel in a persistent popup window instead of the default toolbar popover (the small dropdown that closes when you click outside).

The purpose of this change is to allow you to navigate away from the bookmark panel without losing your work—for example, to copy text from the current page or paste from another window. The window stays open until you click Save, Update, or Cancel.