fix: allow graceful shutdown of sidecar commands on exit (#4561)

Co-authored-by: Lucas Nogueira <lucas@tauri.studio>

.changes/fix-sidecar-shutdown.md

@@ -0,0 +1,5 @@
+---
+"tauri": patch
+---
+
+Emits RunEvent::Exit prior to killing child processes managed by Tauri, allowing graceful shutdown of sidecar binaries.

core/tauri/src/app.rs

@@ -731,13 +731,13 @@ impl<R: Runtime> App<R> {
     let manager = self.manager.clone();
     self.runtime.take().unwrap().run(move |event| match event {
       RuntimeRunEvent::Exit => {
-        app_handle.cleanup_before_exit();
         on_event_loop_event(
           &app_handle,
           RuntimeRunEvent::Exit,
           &manager,
           Some(&mut callback),
         );
+        app_handle.cleanup_before_exit();
       }
       _ => {
         on_event_loop_event(&app_handle, event, &manager, Some(&mut callback));