fix(client): drop renderer before window on shutdown

Reorder the fields of App so renderer is declared before window. Rust
drops struct fields in declaration order, and the renderer owns a
Vulkan surface tied to the window's display-server handle; tearing the
window down first leaves the surface dangling when Renderer::drop runs.

crates/client/src/main.rs

@@ -14,8 +14,8 @@ use winit::window::{Window, WindowId};
 
 #[derive(Default)]
 struct App {
-    window: Option<Window>,
     renderer: Option<renderer::Renderer>,
+    window: Option<Window>,
 }
 
 impl ApplicationHandler for App {