fix(run): stop runs and terminals when the app exits

Closing a window stops what its project started, but a quit that doesn't
close the windows first (the Dock's Quit, the app menu, a logout) exited
with the runs still alive: a server kept its port and the next run of
the configuration failed with "port already in use". On exit the app
now kills every run's process tree and every terminal shell, as the
remote server already does when it shuts down.

Fixes #1691

src-tauri/src/lib.rs

@@ -234,6 +234,7 @@ pub fn run() {
         let _ = &early_opens;
         if let tauri::RunEvent::Exit = event {
             if let Some(state) = app.try_state::<AppState>() {
+                state.host.stop_processes_on_exit();
                 state.host.clear_workspace_edit_history_on_exit();
                 state.host.shutdown_notebooks_on_exit();
             }