fix: measure the swipe speed with the compositor's touch event times (Issue #28)

Pia's log shows the lift arriving 200-300 ms after the last move on every
swipe, so the release looked like a resting finger and nothing glided. The
vendored winit now keeps the Wayland timestamp of each touch event
(take_touch_time), and the fling measures with those times instead of when
the app got around to handling the events. The diagnostics log both gaps and
any event handling that blocks the app for more than 40 ms.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

vendor/winit/src/platform_impl/linux/wayland/seat/touch/mod.rs

@@ -83,6 +83,9 @@ impl TouchHandler for WinitState {
             .touch_map
             .insert(id, TouchPoint { surface, location, frame_of: None });
 
+        // ink-notes patch: keep the event time for `take_touch_time`
+        crate::platform::wayland::push_touch_time(id as u64, TouchPhase::Started, time);
+
         self.events_sink.push_window_event(
             WindowEvent::Touch(Touch {
                 device_id: crate::event::DeviceId(crate::platform_impl::DeviceId::Wayland(
@@ -138,6 +141,8 @@ impl TouchHandler for WinitState {
             None => return,
         };
 
+        // ink-notes patch: keep the event time for `take_touch_time`
+        crate::platform::wayland::push_touch_time(id as u64, TouchPhase::Ended, time);
         self.events_sink.push_window_event(
             WindowEvent::Touch(Touch {
                 device_id: crate::event::DeviceId(crate::platform_impl::DeviceId::Wayland(
@@ -157,7 +162,7 @@ impl TouchHandler for WinitState {
         _: &Connection,
         _: &QueueHandle<Self>,
         touch: &WlTouch,
-        _: u32,
+        time: u32,
         id: i32,
         position: (f64, f64),
     ) {
@@ -192,6 +197,9 @@ impl TouchHandler for WinitState {
 
         touch_point.location = LogicalPosition::<f64>::from(position);
 
+        // ink-notes patch: keep the event time for `take_touch_time`
+        crate::platform::wayland::push_touch_time(id as u64, TouchPhase::Moved, time);
+
         self.events_sink.push_window_event(
             WindowEvent::Touch(Touch {
                 device_id: crate::event::DeviceId(crate::platform_impl::DeviceId::Wayland(