Automations: rebroadcast, buffer time, and auto-cancel

Three things IMP can do on its own, so you don't have to watch every job.

1. Auto-rebroadcast. When a job has been offered and nobody has accepted, IMP can offer it to more interpreters as the start time gets close. You set how close, three hours by default, and how many rounds it can try. Each round only goes to interpreters who haven't seen the job yet.
2. Buffer time. This is for a policy about the gap between an interpreter's jobs: travel, prep, a breather. Say your buffer is sixty minutes, and an interpreter has a job from ten to eleven. When you go to offer them something at eleven-thirty that same day, IMP flags it. They aren't booked then, but they're inside the buffer.
3. A hard overlap shows red. Inside the buffer shows yellow. Neither one stops you. The flag is a nudge to check that interpreter's day before assuming they can make it. You can still offer or assign the job.
4. Auto-cancel. A job that passes its start time with nobody confirmed can cancel itself after a grace period you set, thirty minutes by default. The reason is recorded as unable to fill, and the charges are zeroed, so nothing gets billed by mistake.
5. If an interpreter showed up anyway, you can still confirm them afterward, and the job comes back.
6. The audit log at the bottom records everything that happens in your agency: who did what, when, and to which job. Filter it by type when you're looking for one thing.

Next, the system health check.