Constrain tab bar left of update notice

I've constrained the tab bar to leave 160pt of space on the right for the update accessory view. This ensures the tab bar always appears to the left of the update notice without overlapping.

You're right. Let me check the inheritance chain and find a way to dynamically constrain based on the update accessory view's actual width.

Good! So the inheritance is: TitlebarTabsTahoeTerminalWindow → TransparentTitlebarTerminalWindow → TerminalWindow. This means we can access the updateAccessory from the parent. Let me update the constraints to be dynamic:

Now the tab bar will dynamically constrain itself based on whether the update accessory view exists and has width. It will appear to the left of the update notice when it's visible, and extend to the right edge when it's not.