feat(trackpoint): add left-handed option support

niri-config/src/lib.rs

@@ -250,6 +250,8 @@ pub struct Trackpoint {
     #[knuffel(child, unwrap(argument))]
     pub scroll_button: Option<u32>,
     #[knuffel(child)]
+    pub left_handed: bool,
+    #[knuffel(child)]
     pub middle_emulation: bool,
 }
 
@@ -3902,6 +3904,7 @@ mod tests {
                     scroll_button: Some(
                         274,
                     ),
+                    left_handed: false,
                     middle_emulation: false,
                 },
                 trackball: Trackball {

src/input/mod.rs

@@ -3536,6 +3536,7 @@ pub fn apply_libinput_settings(config: &niri_config::Input, device: &mut input::
         });
         let _ = device.config_scroll_set_natural_scroll_enabled(c.natural_scroll);
         let _ = device.config_accel_set_speed(c.accel_speed);
+        let _ = device.config_left_handed_set(c.left_handed);
         let _ = device.config_middle_emulation_set_enabled(c.middle_emulation);
 
         if let Some(accel_profile) = c.accel_profile {