Assigning a preferred worker to a customer

On the customer card, pick a preferred worker. Optionally a fallback ('if not Maria, then Anya'). Optionally a hard rule ('never a temp').

When generating the schedule, the assistant always assigns the preferred worker first. If they're on holiday or sick, it uses the fallback. If there's no fallback and you've said 'never a temp', it flags the gap for you.

Nothing by default (customers don't see worker names). Optionally, you can turn on 'show worker name' per customer — for loyal elderly clients who like seeing 'Maria is coming on Tuesday'.