docs(skills): 添加 Better Auth 最佳实践与安全配置指南

src/app/api/auth/[...all]/route.ts

@@ -0,0 +1,4 @@
+import { auth } from "@/lib/auth";
+import { toNextJsHandler } from "better-auth/next-js";
+
+export const { GET, POST } = toNextJsHandler(auth);