Turn-scoped maintenance budget divided among a compile-time participant count.
The count cannot be zero:
```compile_fail,E0080
use dope_core::driver::schedule;
fn zero(work: schedule::Maintenance<'static, 'static>) {
drop(work.share::<0>());
}
fn main() {
std::hint::black_box(zero as fn(schedule::Maintenance<'static, 'static>));
}
```