adjust by n-pixels added

[Slackow]

With the n-pixel/fulleye strategy, it makes sense to be able to quickly adjust by a preset number of pixels (e.g 13).

I've added the following under the Angle adjustment menu:

Change the last angle by +n-pixels
Change the last angle by -n-pixels
n-pixels: (number)

This would prevent adjustment hotkeys from being needed to be pressed 10+ times when using these strategies, and allow for more accuracy when inputting these adjustments

Further, this strategy allows the user to have the same accuracy as tall resolution without making their window large, allowing it to be used on platforms that do not allow resizing the window past monitor bounds, like macOS

https://docs.google.com/document/d/1Yz6ORuSVBeQD53y6zn3TJQC1HZUj6QSqYxjIrBUrUHM/edit?tab=t.0