Square tag list corners on MacOS 26

[Earthican]

• Bear Version: 2.6 (13715)
• OS Version: Tahoe 26.0 (25A354)
• What were you doing: Viewing app in full-screen
• What feature did you use: N/A
• What happened: The upper corners of the tag list are squared off in full-screen mode, but rounded when not in full-screen. The bottom corners act correctly.
• What did you expect to happen: rounded corners whether in full-screen or not.