linux: Prompt library fixes (#16850)

This PR fixes two issues:
1. The prompt library window didn't set an `app_id` on Linux, which
caused it to be missing the Zed logo
2. A dangling reference to the window in the Wayland client code, which
caused the prompt library window not to close. See:
https://github.com/zed-industries/zed/pull/13201

Release Notes:

- Linux: Fixed the prompt library not closing on Wayland

---------

Co-authored-by: Junkui Zhang <364772080@qq.com>

crates/gpui/src/platform.rs

@@ -815,7 +815,8 @@ pub struct TitlebarOptions {
     /// The initial title of the window
     pub title: Option<SharedString>,
 
-    /// Whether the titlebar should appear transparent (macOS only)
+    /// Should the default system titlebar be hidden to allow for a custom-drawn titlebar? (macOS and Windows only)
+    /// Refer to [`WindowOptions::window_decorations`] on Linux
     pub appears_transparent: bool,
 
     /// The position of the macOS traffic light buttons

crates/gpui/src/platform/linux/wayland/client.rs

@@ -982,7 +982,8 @@ impl Dispatch<xdg_toplevel::XdgToplevel, ObjectId> for WaylandClientStatePtr {
         let should_close = window.handle_toplevel_event(event);
 
         if should_close {
-            this.drop_window(surface_id);
+            // The close logic will be handled in drop_window()
+            window.close();
         }
     }
 }