This PR implements the [Window Controls Overlay
API](https://web.dev/articles/window-controls-overlay) to let us hide
the menu bar on Windows and Linux and directly embed the window controls
in our tab bar. With #239 merged, we no longer need the menu bar on
these platforms.
The overlaid window controls are transparent so they will take on the
background from the app. I've updated the tab bar to flow properly using
the API's CSS environment variables.
At some point, we may want to update the logic around the symbolColor so
that it can ensure a proper contrast between the background and the
symbols in the window controls. For now, setting them to white works for
all the backgrounds we currently support.
https://github.com/user-attachments/assets/8d19b512-5281-42b9-8abb-ccb9b850061f
This improves the app updater so that it doesn't rely on unreliable
system notifications. Now, a banner in the tab bar will display when an
update is available. Clicking this will prompt the user to restart the
app and complete the installation.
This also updates the tab bar to move to the smaller tab size earlier so
we don't need to make the tab bar scrollable as much.
This adds a new global atom to track whether a window is in full screen.
It also updates the behavior of the tab bar so that it will only add an
extra left indent on macOS windows that are not in full screen.
Otherwise, the indent will be much smaller.
