feat(ops): add tenant admin user management module

Adds /admin-users CRUD on the ops backend, covering listing, plan/role/KOL
toggles, subscription expiry, status flips and password resets, with a
configurable default plan code. The ops console exposes a new top-level
"用户管理" view and reorganises the sidebar so 操作员管理 and 审计日志
move under a "系统设置" group; AccountsView is renamed accordingly.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

deploy/ops-config.yaml

@@ -25,3 +25,6 @@ default_admin:
   display_name: 系统管理员
   email: ""
   password: ""         # 由 OPS_DEFAULT_ADMIN_PASSWORD 环境变量注入（仅在 operator_accounts 为空时生效）
+
+admin_users:
+  default_plan_code: free