fix(repo): untrack the retired Go file that reached dev, and guard it mechanically

go/internal/cli/config_parity.go was committed by a broad `git add` three times
during the #820 campaign. Two of those were caught and reverted (2101d50,
58e8718); the third rode a86ee03 into the #892 merge, so 682 lines of the
retired Go experiment are now tracked on dev — the one and only tracked file
under go/, absent from main, preview, and v2.10.0.

Nothing in src/, the build, the typecheck, or the test path reads from go/, so
this is dead weight in every clone rather than a functional regression. The
commit that introduced it says "untrack ... again" in its own message, which is
how it passed review: the intent was right and the index was not.

.gitignore alone cannot prevent the repeat, because an already-tracked path
stops honoring the ignore rule — so the guard lives in tests/repo-hygiene.test.ts
next to the .codexclaw/gitlink invariants, driven red once by re-adding the file.

Author: lidge-jun

.gitignore

@@ -39,3 +39,10 @@ devlog/**/security-advisory-draft*
 # Test-generated artifacts
 tests/.tmp-*/
 .claude/
+
+# Retired Go native-runtime experiment. `go/` is not part of the build, the
+# typecheck, or the test path, and nothing in `src/` imports it. A single file
+# from it (go/internal/cli/config_parity.go) has now been committed by a broad
+# `git add` three separate times and reached `dev` once — see
+# tests/repo-hygiene.test.ts, which fails if any path here becomes tracked again.
+go/