Fixed: notifications keep their current read state

Delayed notification replies can no longer restore an old unread badge after you mark notifications read. Older lists and errors also cannot replace a newer notification list, and the badge follows the latest count request when list loading and count checks overlap. Repeated clicks on one notification now share a single pending read action, keeping other unread notifications counted correctly. A single read finishing after “mark all read” also cannot reduce the count of notifications that arrived later. Failed read actions remain available to retry.