feat(account): self-service deletion with a 7-day cooling-off period

Request signs out everywhere and freezes paid routes (423 + DB triggers);
signing in within 7 days shows the pending gate with 撤销注销. A periodic
idempotent worker purges personal content afterwards and keeps finance
rows against a tombstoned identity. Read-only admin list.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N4f2nya58RoRu4yEmJgRGE

frontend/src/components/admin/admin-app.tsx

@@ -104,6 +104,7 @@ export function AdminApp({ children }: { children: ReactNode }) {
               { name: "administrators", list: "/admin/administrators", meta: { label: "管理员", icon: <SafetyCertificateOutlined /> } },
               { name: "roles", list: "/admin/roles", meta: { label: "角色权限", icon: <TeamOutlined /> } },
               { name: "customers", list: "/admin/customers", meta: { label: "用户资料", icon: <UserOutlined /> } },
+              { name: "account-deletions", list: "/admin/account-deletions", meta: { label: "注销申请", icon: <UserOutlined /> } },
               { name: "products", list: "/admin/products", meta: { label: "商品权益", icon: <ShoppingOutlined /> } },
               { name: "subscriptions", list: "/admin/subscriptions", meta: { label: "订阅", icon: <CreditCardOutlined /> } },
               { name: "orders", list: "/admin/orders", meta: { label: "订单", icon: <DatabaseOutlined /> } },