fix(wayland): prevent libinput unset axis error on scroll

[uint82]

Description

This PR fixes an issue where scrolling a mouse wheel under Wayland causes libinput to aggressively spam the console with the following error:
libinput error: client bug: value requested for unset axis

The Cause:
Currently, when a PointerScrollWheelEvent is received, the code unconditionally requests both Axis::Horizontal and Axis::Vertical values. If the physical mouse only triggered a vertical scroll, requesting the horizontal axis triggers a safety check inside libinput, resulting in the "client bug" error.

The Fix:
I imported the PointerScrollEvent trait and wrapped the axis value requests in an if btn.has_axis(...) check. If the axis wasn't triggered by the hardware, it safely defaults to 0 instead of querying libinput.

Changes Made

• Added use input::event::pointer::PointerScrollEvent; to imports.
• Updated the PointerEvent::ScrollWheel(btn) match arm to verify axis existence before calculating delta_x and delta_y.

Additional Context

I ran into this while building a macro recorder for Wayland. My engine bypasses user-space jitter by using evdev directly for recording, but I am still using rdev to listen for global hotkeys (like F-keys) to start/stop the macros.

Whenever I scrolled my mouse wheel, this Wayland axis bug would trigger and spam my macro engine's terminal output. This fix keeps the console completely clean!