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/TASKS/TASK-013B-ECR013B.yaml

@@ -0,0 +1,21 @@
+id: TASK-013B-ECR013B
+ecr: ECR-013B
+title: AccountLifecycle Contract Definition
+role: architect
+status: contract
+change_level: L2
+parent: WAVE0-FROZEN
+predecessor: ECR-013A
+inputs:
+  - docs/WAVE0/
+  - .ai/domain/entity-catalog.md
+  - .ai/product/feature-spec/ops-account-lifecycle.md
+outputs:
+  - docs/ECR/ECR-013B-account-lifecycle.md
+  - docs/BACKEND_DESIGN/BD-2026-013B-account-lifecycle.md
+  - docs/CONTRACT_DIFF/ECR-013B.yaml
+  - docs/HANDOFF/ECR-013B-architect-to-engineer.md
+acceptance:
+  - L0-L4 filled
+  - No coding / no migration files
+  - soft-delete out of scope