Passes and tours — multi-flight credits and ground experiences

Passes are pre-bought flight credits. Tours are non-flight experiences sold alongside flights.

Passes (Passes tab):
- Create a **template** — name, total flight credits included, validity window, eligible routes (or "any"), price.
- A customer buys the template → an **issued pass** is minted on their account.
- At booking time, the customer can apply pass credits to cover all or part of the fare.
- Useful for: corporate fly-away programs, frequent-flyer 10-packs, gift-giving.

Tours (Tours tab):
- Standalone or paired with a flight. Examples: scenic 30-min helicopter loop, ground transfer to a vineyard, post-arrival city tour.
- Capacity is per-tour (own headcount cap, own timeslots).
- Bookings appear in the same manifest as flights, flagged as tour bookings.

Both pass purchases and tour bookings post to Accounting via the standard order pipeline.