golangci-lint bundles gofumpt v0.8.0, which formats code differently
from the v0.9.2 we pin in go.mod. Enforcing formatting through
golangci-lint may therefore disagree with `just format`.
Remove gofumpt from golangci-lint's formatters and instead run the
pinned `go tool gofumpt` as a standalone check via a new
scripts/gofumpt-check.sh, wired into CI, `just lint`, and `make lint`.
goimports stays in golangci-lint; it's stable across versions and
nothing runs a competing copy of it.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
