refactor(tenant): refine menu scope boundaries and document plan/tenant menu design

src/utils/tenant.ts

@@ -0,0 +1,16 @@
+import { appConfig } from "@/settings";
+import { PLATFORM_TENANT_ID } from "@/constants";
+
+/**
+ * 是否启用多租户
+ */
+export const isTenantEnabled = () => appConfig.tenantEnabled;
+
+/**
+ * 判断是否平台租户
+ *
+ * @description
+ * 平台租户不参与套餐与菜单配置
+ */
+export const isPlatformTenantId = (tenantId?: string | number) =>
+  Number(tenantId) === PLATFORM_TENANT_ID;