breadbox: steal focus on open, close on unfocus

Switch KeyboardMode to Exclusive so Hyprland hands keyboard focus to
breadbox immediately on creation. Add an EventControllerFocus on the
window that calls close() the moment focus leaves (click outside,
alt-tab, compositor focus change, etc.).

src/main.rs

@@ -331,7 +331,7 @@ fn run_ui(entries: Vec<(String, String)>) {
 
         window.init_layer_shell();
         window.set_layer(Layer::Overlay);
-        window.set_keyboard_mode(KeyboardMode::OnDemand);
+        window.set_keyboard_mode(KeyboardMode::Exclusive);
         window.set_anchor(Edge::Top, true);
         window.set_exclusive_zone(-1);
 
@@ -474,6 +474,15 @@ fn run_ui(entries: Vec<(String, String)>) {
             }
         });
 
+        // Close when focus leaves the window (click outside, alt-tab, etc.)
+        let window_foc = window.clone();
+        let focus_ctrl = gtk4::EventControllerFocus::new();
+        focus_ctrl.connect_leave(move |_| {
+            cleanup_pid();
+            window_foc.close();
+        });
+        window.add_controller(focus_ctrl);
+
         // Cleanup pid when window is destroyed for any reason
         window.connect_destroy(|_| cleanup_pid());