feat(protocol): add wl_surface arg to create_window in weft-shell-unstable-v1

Adds an optional (allow-null) wl_surface argument to zweft_shell_manager_v1::create_window.
Shell-owned windows pass null; app-backed windows pass the backing wl_surface so the
compositor can correlate the surface with a session_id from weft-appd. Updates
WeftShellWindowData to store the surface, and updates the CreateWindow handler in state.rs
and the two protocol unit tests.

crates/weft-compositor/src/protocols/mod.rs

@@ -28,6 +28,7 @@ pub struct WeftShellWindowData {
     pub app_id: String,
     pub title: String,
     pub role: String,
+    pub surface: Option<wayland_server::protocol::wl_surface::WlSurface>,
     pub closed: std::sync::atomic::AtomicBool,
 }
 
@@ -55,6 +56,7 @@ mod tests {
             app_id: "com.example.test".into(),
             title: "Test Window".into(),
             role: "normal".into(),
+            surface: None,
             closed: std::sync::atomic::AtomicBool::new(false),
         };
         assert_eq!(d.app_id, "com.example.test");
@@ -69,6 +71,7 @@ mod tests {
             app_id: String::new(),
             title: String::new(),
             role: String::new(),
+            surface: None,
             closed: std::sync::atomic::AtomicBool::new(false),
         };
         assert!(!d.closed.load(Ordering::Relaxed));

crates/weft-compositor/src/state.rs

@@ -454,6 +454,7 @@ impl Dispatch<ZweftShellManagerV1, ()> for WeftCompositorState {
                 app_id,
                 title,
                 role,
+                surface,
                 x,
                 y,
                 width,
@@ -465,6 +466,7 @@ impl Dispatch<ZweftShellManagerV1, ()> for WeftCompositorState {
                         app_id,
                         title,
                         role,
+                        surface,
                         closed: std::sync::atomic::AtomicBool::new(false),
                     },
                 );

protocol/weft-shell-unstable-v1.xml

@@ -74,6 +74,8 @@
            summary="initial window title"/>
       <arg name="role"    type="string"
            summary="window role hint (normal, dialog, panel, overlay)"/>
+      <arg name="surface" type="object" interface="wl_surface" allow-null="true"
+           summary="wl_surface backing this window slot; null for shell-owned windows"/>
       <arg name="x"       type="int"
            summary="requested x position in compositor logical coordinates"/>
       <arg name="y"       type="int"