GTK only honors whole-number GDK_SCALE values, so persisting 1.6 or 1.25
verbatim left GTK apps without a usable scale. Round to the nearest whole
factor when writing monitors.lua.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Hyprland only takes scales where the mode divides into whole logical
pixels (in 1/120 steps), so picking 3x on a 1280x800 QEMU display threw
a red error overlay and silently kept the old scale. Round the request
up to the nearest clean divisor instead, so 3x becomes 3.2x.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Hyprland can report a scale set to 3 as something like 3.0000000000000004.
The previous directional comparison treated that as above the 3 preset, so
Super+Alt+Slash (scale down) would stay at 3 instead of reaching 2.
Snap the reported scale to the nearest preset first, then step up/down.
Add a regression test for the floating-point case.
