feature: locked aspect ration resize mode

we could trigger it by holding shift in our skhd/hotkey configs.
to resize windows using mouse modifier, add a new resize mode for ratio lock.
This will allow us to resize a window and keep its proportions.

Start by tracing the existing mouse-modifier resize modes and the resize event handling referenced by the skhd/hotkey configuration. Done means a new ratio-lock mode can be triggered with Shift and resizing a window preserves its proportions.

Written by the indexing model from the issue text.