feat: setup barrelsby for automatic barrel file generation

Add barrelsby as a dev dependency with a `generate-barrels` npm script and a `barrelesby.json` config targeting `./src`. This automates creation of barrel/index files to simplify imports across the project.

src/data/models/auth/login_response.ts

@@ -0,0 +1,43 @@
+/**
+ * 登录响应
+ * 原始 Dart: LoginResponse (lib/data/models/auth/auth_response.dart)
+ */
+import { User } from "../user/user";
+
+export class LoginResponse {
+  readonly user: User;
+  readonly token: string;
+  readonly refreshToken: string;
+
+  constructor(params: { user: User; token: string; refreshToken?: string }) {
+    this.user = params.user;
+    this.token = params.token;
+    this.refreshToken = params.refreshToken ?? "";
+    Object.freeze(this);
+  }
+
+  toJson(): Record<string, unknown> {
+    return {
+      user: this.user.toJson(),
+      token: this.token,
+      refreshToken: this.refreshToken,
+    };
+  }
+
+  static fromJson(json: Record<string, unknown>): LoginResponse {
+    const token = json.token;
+    if (typeof token !== "string") {
+      throw new Error("LoginResponse.token is required and must be a string");
+    }
+    const userJson = json.user;
+    if (typeof userJson !== "object" || userJson === null) {
+      throw new Error("LoginResponse.user is required and must be an object");
+    }
+    return new LoginResponse({
+      user: User.fromJson(userJson as Record<string, unknown>),
+      token,
+      refreshToken:
+        typeof json.refreshToken === "string" ? json.refreshToken : undefined,
+    });
+  }
+}