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>

tools/verify_adr_lang_pairs.py

@@ -24,7 +24,7 @@ import sys
 from pathlib import Path
 
 ADR_FILENAME_RE = re.compile(r"^ADR-(\d{4})-[a-z0-9_-]+\.md$")
-TITLE_RE = re.compile(r"^# ADR-(\d{4}):")
+TITLE_RE = re.compile(r"^# ADR-(\d{4})\b")
 
 
 def _normalize(text: str) -> str: