Stack context: second layer of the Go lint gate stack, built on the
exclusion fix below.
Why: adds commented-out code detection and a `log/slog` ban to the main
config, plus a new-code-only pass requiring reasons on lint
suppressions, flagging ignored errors (including `_, _ = w.Write(...)`),
and banning `time.Sleep` in tests. Fixing the hits surfaced a real bug:
GitLab warnings went to the wrong logger. The new-code pass resolves
symlinked checkout paths so it does not silently report nothing.
Validation: both configs report 0 issues; each seeded violation is
caught; `make pre-commit` passed.
> Xum acted for Mike to open this PR.
Michael Suchacz
7517301ffa