Title new sessions from their first chat

The one-shot from the session quick actions now also runs once when a
draft session becomes real, summarizing the opening message instead of
leaving the "Session N" placeholder.

Failures stay silent on this path: the user did not ask for a title, so
a busy runtime must not raise an error banner. A rename made while the
request is queued wins over its result.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/app.rs

@@ -771,7 +771,7 @@ impl App {
             Message::RetitleSession(session_id) => {
                 self.session_menu = None;
                 #[cfg(target_os = "macos")]
-                self.request_title(session_id);
+                self.retitle_session(session_id);
                 #[cfg(not(target_os = "macos"))]
                 {
                     let _ = session_id;