docs(ECR-013B): 启动 AccountLifecycle 契约定义

Human Start Authorization：UserStatus 状态机 Spec/BD/contract_diff；
禁止 coding，待 Approve + coding Start Authorization。

Co-authored-by: Cursor <cursoragent@cursor.com>

docs/HANDOFF/ECR-013B-architect-to-engineer.md

@@ -0,0 +1,36 @@
+# HANDOFF — ECR-013B Architect → Engineer
+
+## Gate
+
+**Parent:** WAVE0-FROZEN (`27f27a1`)  
+**Predecessor:** ECR-013A **Closed**
+
+**Start Authorization: 2026-08-07（Human）→ Contract Definition only**  
+**ECR-013B + BD-2026-013B = Draft** — **禁止改 `apps/`** 直至：
+
+1. Human **Approve** ECR-013B + BD-2026-013B  
+2. 另发 **coding Start Authorization**
+
+## Consume
+
+1. `.ai/product/feature-spec/ops-account-lifecycle.md`  
+2. ECR / PRODUCT / ENGINEERING / BD / `docs/CONTRACT_DIFF/ECR-013B.yaml`  
+3. `.ai/domain/boundary-rules.md` · `glossary.yaml` · `entity-catalog.md`  
+
+## Do（仅 Approve + coding auth 后）
+
+按 ENGINEERING_SPEC Implement order。
+
+## Do not
+
+- soft-delete / `deleted`  
+- 真支付 · UGC · Prompt  
+- 跳过 Security AC（含 C 端拒绝）  
+- 重做 RBAC（仅 additive permission）  
+
+## Return
+
+1. HANDOFF engineer→reviewer  
+2. TEST_REPORT 映射全部 AC-ID  
+3. CODE_REVIEW  
+4. `ess-validate --phase review --ecr ECR-013B`