Until now the only CI on this repo was dev-bakery.yml / dev-bread-theme.yml
(both `cargo build --bin` only) and the release workflows — so nothing here
was ever clippy'd or tested in CI, and the entire per-monitor GTK bind
module in bread-theme (feature-gated behind `gtk`) never even compiled in
CI. A push to `main` publishes a dev build; it should be checked first.
Runs on feature/**, fix/**, and main: clippy + test, once plain and once
with --features gtk.
fmt is not gated yet — the tree isn't `cargo fmt` clean (27 files) and a
mass reformat would collide with every open PR. Separate change.
