feat: Set chat name (#4974)

Set chat name with `/name` so they appear in the codex resume page:


https://github.com/user-attachments/assets/c0252bba-3a53-44c7-a740-f4690a3ad405

codex-rs/tui/src/app.rs

@@ -381,6 +381,9 @@ impl App {
             AppEvent::OpenReviewCustomPrompt => {
                 self.chat_widget.show_review_custom_prompt();
             }
+            AppEvent::SetSessionName(name) => {
+                self.chat_widget.begin_set_session_name(name);
+            }
             AppEvent::FullScreenApprovalRequest(request) => match request {
                 ApprovalRequest::ApplyPatch { cwd, changes, .. } => {
                     let _ = tui.enter_alt_screen();