✨ Add proportional window sizing for screen transitions

[cipher-shad0w]

Closes #713

Implements proportional window sizing when moving windows between displays of different sizes. Previously, windows would retain their absolute pixel dimensions
when transitioning between screens, leading to inconsistent behavior. This PR introduces screen-aware calculations that maintain window proportions relative to
each display's dimensions.

[cipher-shad0w]

This implementation applies proportional sizing only to standard window positions (halves, quarters,
thirds, fourths, maximize, etc.) when moving between screens.

What's supported ✅

• All standard positions with frameMultiplyValues (halves, quarters, thirds, fourths)
• Maximize and almost-maximize actions

What's NOT supported ❌

• Custom Actions - These will use their defined pixel/percentage values as-is
• Special actions (center, undo, move, grow/shrink, etc.)

Technical reasoning

The feature checks for action.direction.frameMultiplyValues != nil to determine if proportional sizing
should be applied. Custom actions don't have frameMultiplyValues as they define their dimensions through
different properties (width, height, unit, positionMode, etc.).

[mrkai77]

This is a really good attempt at tackling the issue, thank you so much for taking the time to dive into it! Unfortunately, the approach isn’t quite correct. The main sign that this method isn’t ideal is that the preview window would no longer accurately reflect the frame of the window on the new screen. Action frames shouldn’t be calculated inside WindowEngine; its role should focus on executing them instead.

The correct approach would be to calculate the proportional frame within LoopManager.changeAction, right when the user selects the action. This both produces the right behavior and makes the overall implementation much simpler.

While reviewing this PR, I ended up putting together my own solution for the issue, which I’ll be merging (#874). I’d encourage you to take a look at it, I’d be more than happy to walk you through any of the changes if you’d like! Once again, I really appreciate your effort and initiative here. It means a lot that you took the time to work on this :)