ci: API 分層檢查 + LLM 測試移至 Nightly

CI 強化:
- 新增 API Layer Check (#96): services/repositories/models 分層規則
- LLM 測試移至 nightly-llm.yaml (CPU 推理 ~300s/測試)

分層規則:
- services 禁止引用 api/routers
- repositories 禁止引用 services
- models 禁止引用業務層

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/api/src/core/__init__.py

@@ -1 +1,30 @@
 # Core module
+# ADR-027: Incident-Approval 同步架構 (2026-03-26)
+
+from .constants import (
+    APPROVAL_TO_INCIDENT_STATUS,
+    APPROVAL_TTL_SECONDS,
+    DECISION_TTL_SECONDS,
+    INCIDENT_ACTIVE_STATUSES,
+    INCIDENT_TTL_SECONDS,
+    REDIS_KEY_APPROVAL,
+    REDIS_KEY_DECISION,
+    REDIS_KEY_INCIDENT,
+    REDIS_KEY_PENDING,
+)
+from .unit_of_work import UnitOfWork
+
+__all__ = [
+    # Constants (ADR-027)
+    "INCIDENT_TTL_SECONDS",
+    "APPROVAL_TTL_SECONDS",
+    "DECISION_TTL_SECONDS",
+    "REDIS_KEY_INCIDENT",
+    "REDIS_KEY_APPROVAL",
+    "REDIS_KEY_PENDING",
+    "REDIS_KEY_DECISION",
+    "APPROVAL_TO_INCIDENT_STATUS",
+    "INCIDENT_ACTIVE_STATUSES",
+    # Unit of Work (ADR-027)
+    "UnitOfWork",
+]