Show a "Draft" indicator in Inbox conversation rows

When a conversation has an unsent reply draft, show a clear "Draft" label in its Inbox row, ideally followed by a preview of the draft text, similar to Facebook’s Messenger.

This should work for both manually written and AI-generated drafts. Currently, the row still shows the last message, so you have to open each conversation to see whether a draft is waiting.

This would make it easier to find unfinished replies and drafts that need review. Remove the indicator when the draft is sent or discarded.