Adjusts Nova dropdown submenu styling to use a larger border radius (rounded-lg instead of rounded-md) across Base and Radix examples, generated registry JSON, and the Nova CSS, making submenu visuals consistent with the rest of the theme. Impact is purely UI/polish—submenus will render with softer corners in all Nova dropdown variants. Concern: the format check is failing, so the PR may not meet repo formatting/lint requirements despite the small change set.