feat(wayland): add touchscreen input support

Bind wl_touch seat capability and route the primary touch contact through the existing left-button input path for drawing, toolbar, modal, and toast interactions. Add touch state tracking and cancellation cleanup for stale toolbar, board-pan, and suppressed-release state.

Author: devmobasa

src/backend/wayland/handlers/mod.rs

@@ -3,7 +3,7 @@
 use smithay_client_toolkit::{
     delegate_compositor, delegate_keyboard, delegate_layer, delegate_output, delegate_pointer,
     delegate_pointer_constraints, delegate_registry, delegate_relative_pointer, delegate_seat,
-    delegate_shm, delegate_xdg_shell, delegate_xdg_window,
+    delegate_shm, delegate_touch, delegate_xdg_shell, delegate_xdg_window,
 };
 
 use super::state::WaylandState;
@@ -15,6 +15,7 @@ delegate_layer!(WaylandState);
 delegate_seat!(WaylandState);
 delegate_keyboard!(WaylandState);
 delegate_pointer!(WaylandState);
+delegate_touch!(WaylandState);
 delegate_pointer_constraints!(WaylandState);
 delegate_relative_pointer!(WaylandState);
 delegate_registry!(WaylandState);
@@ -36,4 +37,5 @@ mod seat;
 mod shm;
 #[cfg(tablet)]
 mod tablet;
+mod touch;
 mod xdg;

src/backend/wayland/handlers/seat.rs

@@ -53,6 +53,19 @@ impl SeatHandler for WaylandState {
             }
         }
 
+        if capability == Capability::Touch {
+            info!("Touch capability available");
+            match self.seat_state.get_touch(qh, &seat) {
+                Ok(touch) => {
+                    debug!("Touch initialized");
+                    self.touch = Some(touch);
+                }
+                Err(err) => {
+                    warn!("Touch initialization failed: {}", err);
+                }
+            }
+        }
+
         #[cfg(tablet)]
         if let Some(manager) = &self.tablet_manager
             && self.tablet_seats.is_empty()
@@ -79,6 +92,11 @@ impl SeatHandler for WaylandState {
             self.current_pointer_shape = None;
             self.cursor_hidden = false;
         }
+        if capability == Capability::Touch {
+            info!("Touch capability removed");
+            self.touch = None;
+            self.cancel_active_touch_sequence();
+        }
     }
 
     fn remove_seat(&mut self, _conn: &Connection, _qh: &QueueHandle<Self>, _seat: wl_seat::WlSeat) {