This repo had no pull_request workflow at all — release.yml runs only
after merge, so its `cargo fmt --check` gate was the first thing to see
new code, and an unformatted commit killed the release job before it
could build, tag, or publish (run for 2301c57).
Add pr-checks.yml, mirroring release.yml's gates in the same order so a
green PR implies the release clears its own gates:
cargo fmt --check
cargo clippy --locked --all-targets -- -D warnings
cargo test --locked
One job, not three: bootstrapping the toolchain costs more than the
checks, so parallel jobs would pay it three times for no wall-clock win.
Cargo registry and target/ are cached on Cargo.lock. The crate is
already clean at `-D warnings`, so clippy starts green.
Co-Authored-By: Claude <noreply@anthropic.com>
