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>

docs/adr/ADR-0012-api-host-io-message-schema.md

@@ -18,7 +18,7 @@ We define stable, minimal message schemas for Host ↔ IO_CPU so that:
 - IO_CPU-internal fan-out/aggregation can evolve independently,
 - completion and failure propagation is deterministic.
 
-We also require PE-tagging (A 방식): each shard explicitly carries (sip,cube,pe)
+We also require PE-tagging (Scheme A): each shard explicitly carries (sip,cube,pe)
 so IO_CPU can deterministically route/fan-out without relying on PA decoding.
 
 ---
@@ -93,7 +93,7 @@ Rules:
 Mandatory fields:
 
 - common envelope fields (D3)
-- destination placement tags (A 방식):
+- destination placement tags (Scheme A):
   - `dst_sip: int`
   - `dst_cube: int`
   - `dst_pe: int`
@@ -130,7 +130,7 @@ Notes:
 Mandatory fields:
 
 - common envelope fields (D3)
-- source placement tags (A 방식):
+- source placement tags (Scheme A):
   - `src_sip: int`
   - `src_cube: int`
   - `src_pe: int`
@@ -183,7 +183,7 @@ Tensor arg (mandatory):
 
 - `shards: list[TensorShard]`
 
-`TensorShard` MUST have (A 방식 강제):
+`TensorShard` MUST have (Scheme A enforced):
 
 - `sip: int`
 - `cube: int`