ADR: bilingual structure — EN canonical in adr/, KO mirror in adr-ko/

Establish English as the canonical ADR language with Korean translations
held in a parallel docs/adr-ko/ tree as derived artifacts (1:1 mirror).
Promotion from adr-proposed/ to adr/ now writes English to adr/ and the
Korean to adr-ko/; bidirectional sync rule documented in CLAUDE.md.

- Migrate 30 ADRs in docs/adr/: 28 Korean-only translated to English,
  2 bilingual pairs (ADR-0020, ADR-0023) consolidated (.en.md suffix
  dropped). ADR-0023 EN regenerated against KO source which had newer
  HW Realization Notes (D16-D23) section.
- docs/adr-history/ left frozen by design (transitional state).
- CLAUDE.md (Part 2): update ADR Lifecycle for 4-folder layout, mark
  docs/adr-ko/ as a Derived Artifact, add ADR Translation Discipline
  section covering bidirectional sync, conflict resolution (EN wins),
  and proposed-language freedom.
- tools/verify_adr_lang_pairs.py: new verification tool checking pair
  completeness, filename mirroring, ADR-ID match, Status byte-equality.
  Pre-commit hook intentionally not added; run on demand or in CI.
- tests/test_verify_adr_lang_pairs.py: 11 cases including CRLF/LF
  normalization, em-dash title separator, underscore-slug edge case.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/test_verify_adr_lang_pairs.py

@@ -92,6 +92,18 @@ def test_crlf_normalization(tmp_path: Path) -> None:
     assert v.verify(tmp_path) == []
 
 
+def test_em_dash_title_separator_recognized(tmp_path: Path) -> None:
+    """ADR-0033 uses ' — ' instead of ': ' between ADR-NNNN and the title."""
+    en = tmp_path / "docs/adr/ADR-0033-foo-bar.md"
+    ko = tmp_path / "docs/adr-ko/ADR-0033-foo-bar.md"
+    en.parent.mkdir(parents=True, exist_ok=True)
+    ko.parent.mkdir(parents=True, exist_ok=True)
+    body = "## Status\n\nAccepted\n\n## Context\n\nbody\n"
+    en.write_text("# ADR-0033 — Latency Model\n\n" + body, encoding="utf-8")
+    ko.write_text("# ADR-0033 — Latency Model\n\n" + body, encoding="utf-8")
+    assert v.verify(tmp_path) == []
+
+
 def test_underscore_in_slug_recognized(tmp_path: Path) -> None:
     """ADR-0013 uses an underscore in its slug; the regex must accept it."""
     _make_adr(tmp_path / "docs/adr/ADR-0013-ver-verification_strategy.md", "0013")