Implement non-uniform brightness step adjustments (#5525)

* Implement non-uniform brightness step adjustments

Add logic for non-uniform step size adjustments based on current brightness level.

* Ensure percentages are moved in a consistent manner so we don't get rounding errors

* Ensure we don't go below 1%

To prevent screen from turning off entirely on some models

---------

Co-authored-by: David Heinemeier Hansson <david@hey.com>

bin/omarchy-brightness-display

@@ -14,6 +14,31 @@ for candidate in amdgpu_bl* intel_backlight acpi_video*; do
   fi
 done
 
+# Current brightness percentage
+current=$(brightnessctl -d "$device" -m | cut -d',' -f4 | tr -d '%')
+
+# Apply non-uniform step size: 1% steps if at or below 5%, otherwise set an
+# absolute target percentage to avoid raw backlight rounding causing uneven OSD steps.
+if [[ $step == "+5%" ]]; then
+  if (( current < 5 )); then
+    (( target = current + 1 ))
+  else
+    (( target = current + 5 ))
+  fi
+
+  (( target > 100 )) && target=100
+  step="$target%"
+elif [[ $step == "5%-" ]]; then
+  if (( current <= 5 )); then
+    (( target = current - 1 ))
+  else
+    (( target = current - 5 ))
+  fi
+
+  (( target < 1 )) && target=1
+  step="$target%"
+fi
+
 # Set the actual brightness of the display device.
 brightnessctl -d "$device" set "$step" >/dev/null