refactor(device): name the probe's bounds ProbeTimeouts

Across the workspace a deadline is an `Instant` and a duration that bounds a wait is a timeout, and `host_lock::lock_within` two modules away keeps exactly that distinction: it turns the duration it is given into `let deadline = Instant::now() + …`. `ProbeDeadlines` held seven `Duration`s and no `Instant`, every one handed to `timeout(…)` or to that lock wait. The struct becomes `ProbeTimeouts`, and the names that hold one follow it: the `deadlines` field of `Enumerator` and of `PassContext`, the parameters and locals called `deadlines`, the tests' `quick_deadlines`, and the seven doc words that describe the struct. 69 tokens change and nothing else; the real deadlines in `host_lock.rs` and `pairing.rs` keep their name.