Enabling CWD Saving for Image-Gen (#13607)

Codex now saves the generated image on to your current working
directory.

codex-rs/tui/src/chatwidget/tests.rs

@@ -6053,6 +6053,7 @@ async fn image_generation_call_adds_history_cell() {
             status: "completed".into(),
             revised_prompt: Some("A tiny blue square".into()),
             result: "Zm9v".into(),
+            saved_path: None,
         }),
     });