feat(ECR-006): 落地运营后台 Phase A（admin API + admin-h5）

新增独立鉴权的 /api/v1/admin 与 Vue 控制台；会员授予与审计同事务，并补集成/单测。

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

docs/TASKS/TASK-006-ECR006.yaml

@@ -0,0 +1,18 @@
+id: TASK-006-ECR006
+ecr: ECR-006
+title: Ops admin Phase A implementation
+role: engineer
+status: open
+change_level: L2
+inputs:
+  - docs/HANDOFF/ECR-006-architect-to-engineer.md
+  - docs/BACKEND_DESIGN/ECR-006-ops-admin-phase-a.md
+  - .ai/product/feature-spec/ops-admin.md
+outputs:
+  - apps/api admin package + migration
+  - apps/admin-h5 Vue shell
+  - docs/TEST_REPORT/ECR-006.md
+acceptance:
+  - Spec T1-T5
+  - go test ./...
+  - admin-h5 build