Improve Wayland scroll behavior

[gokselk]

This PR enhances the scroll input handling in Wayland by introducing source-specific scroll adjustments:

• For mouse wheels:
  • Uses discrete values when available
  • Falls back to normalizing continuous values using standard 15-degree wheel clicks
• For touchpads and other input sources:
  • Applies a 1/10 scale factor to smooth out scrolling behavior

This change helps address the oversensitive scrolling reported in #3142, particularly making touchpad scrolling more consistent with X11 behavior and other terminal emulators.

Tested on KDE Plasma 6 Wayland with 3-line scroll increments, showing improved consistency with system-wide scrolling behavior.

[gokselk]

Identified inconsistent behavior across different DPI settings. This PR is currently a draft while I investigate potential solutions.