Deliver BAT-001: bootstrap trex-core + port slot pure domain

Implement REQ-001~004 (dcy-001): scaffold the trex-core package
(pyproject, trex_core/, tests/), port the slot pure domain into
trex_core.domain.slot with import rewrites, add the EXPECTED_SLOT_FIELDS
contract guard (test_contract), and port the state/service unit tests.

Verification: 56 passed, ruff clean, import sweep shows zero external
deps, public __all__ exposes no infra symbols, contract negative case
reproduced. Align project-structure/runtime-flows baselines to the real
tree. Sync SDLC tracking: REQ-001~004 → Implemented, BAT-001 →
release-candidate.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/srs/index.md

@@ -74,14 +74,20 @@
 
 ## Next Requirement ID
 
-- Current: `REQ-001`
+- Current: `REQ-005`
 - Rule: `Requirement Register`에 있는 가장 큰 REQ 번호보다 정확히 1 커야 한다.
 
 ## Requirement Register
 
 | ID | Title | Type | Status | Priority | Owner | Link |
 | --- | --- | --- | --- | --- | --- | --- |
+| REQ-001 | trex-core Python 프로젝트 부트스트랩 | Installation | Implemented | High | project maintainers | [req-001](./Installation/req-001_trex-core-bootstrap.md) |
+| REQ-002 | slot 순수 도메인 이식 및 공개 API 확정 | Interface | Implemented | High | project maintainers | [req-002](./Interface/req-002_slot-pure-domain-port.md) |
+| REQ-003 | slot 도메인 단위테스트 이식 및 컬럼 계약 가드 | Testing | Implemented | High | project maintainers | [req-003](./Testing/req-003_slot-domain-tests-and-contract-guard.md) |
+| REQ-004 | baseline 문서 planned→실제 정합 | Documentation | Implemented | Medium | project maintainers | [req-004](./Documentation/req-004_baseline-doc-alignment.md) |
 
 ## Recent Change Log Summary
 
-- 없음
+- 2026-06-03 :: REQ-001~004 Approved → Implemented — BAT-001 verification evidence 기반. (confirm-req-implemented)
+- 2026-06-03 :: REQ-001~004 Proposed → Approved — 승인 게이트 통과. (confirm-req)
+- 2026-06-03 :: REQ-001~004 최초 생성(Proposed) — dcy-001 FR-1~FR-5 분해. (draft-req)