Making `AgentState` `Copy` in the preceding commit is a change to every
consumer of the type, not to the crate that declares it. `hive-c0re` grew its
own consumer while this branch was in review, and under `-D pedantic` a
one-byte enum taken by reference is `trivially_copy_pass_by_ref` and a
`.clone()` on it is `clone_on_copy`. Neither crate is wrong alone; the merge
is.
`decide` now takes the state by value and the call sites drop the `&`. No
behaviour change — the function only matches on the value.
8dbccd5578