When there are no upcoming conferences, the page now displays a
friendly message informing users that there are no conferences at
this time and inviting them to check back later or browse past
conferences.
Additionally, the calendar export buttons are now conditionally
displayed only when there are conferences (current or past) available.
Fixes#2707
Co-Authored-By: Claude (claude-opus-4-5) <noreply@anthropic.com>
9473946c86