v0.6.1

Fixed

• Day passes and single-session packages no longer disappear into old records: buying another 1-day gym pass or 1-session class while a prior purchase of the same package was still "active" silently merged the new sale into the old subscription instead of recording a new visit — so staff would see nothing new after taking payment. Every single-visit sale now always creates its own record.
• Packages can no longer be saved with a Duration of 0 and no Session Count — that combination produced subscriptions that never expired and were treated as permanently active, which is what caused the bug above.