feat(common): 新增基础设施 HAR（网络/鉴权/日志/状态/工具）

common/src/main/ets/network/ApiError.ets

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+/**
+ * 统一错误模型：业务错误码 / HTTP 状态码 / 网络异常。
+ * 继承 Error 以符合 ArkTS 的 throw 限制（只能抛 Error 及其子类）。
+ */
+export class ApiError extends Error {
+  readonly code: number;
+  readonly isNetworkError: boolean;
+
+  constructor(code: number, message: string, isNetworkError: boolean = false) {
+    super(message);
+    this.code = code;
+    this.isNetworkError = isNetworkError;
+  }
+
+  static network(detail: string): ApiError {
+    return new ApiError(-1, `网络请求失败: ${detail}`, true);
+  }
+
+  static http(statusCode: number): ApiError {
+    return new ApiError(statusCode, `HTTP 状态码异常: ${statusCode}`, false);
+  }
+
+  static business(code: number, message: string): ApiError {
+    return new ApiError(code, message, false);
+  }
+}

common/src/main/ets/network/ApiResult.ets

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+/**
+ * 统一响应包装：与后端约定 code / message / data 结构。
+ */
+export class ApiResult<T> {
+  code: number;
+  message: string;
+  data: T;
+
+  constructor(code: number, message: string, data: T) {
+    this.code = code;
+    this.message = message;
+    this.data = data;
+  }
+
+  isSuccess(): boolean {
+    return this.code === 0;
+  }
+}

common/src/main/ets/network/AuthInterceptor.ets

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+import { HttpInterceptor } from './HttpInterceptor';
+import { SessionManager } from '../state/SessionStore';
+
+/**
+ * 鉴权拦截器：请求前注入 Authorization 头；401 时清空会话（登出）。
+ *
+ * TODO(鉴权): 401 时的 token 刷新 + 原请求重放（防并发刷新）需在
+ * 后端 refresh 接口约定后实现，当前先清空会话交由上层跳登录。
+ */
+export class AuthInterceptor implements HttpInterceptor {
+  onRequest(header: Record<string, string>): Record<string, string> {
+    const session = SessionManager.get();
+    if (session.token.length > 0) {
+      header['Authorization'] = `Bearer ${session.token}`;
+    }
+    return header;
+  }
+
+  onResponse(responseCode: number, result: string): void {
+    if (responseCode === 401) {
+      SessionManager.get().clear();
+    }
+  }
+}

common/src/main/ets/network/HttpClient.ets

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+import { http } from '@kit.NetworkKit';
+import { HttpInterceptor } from './HttpInterceptor';
+import { ApiError } from './ApiError';
+
+/**
+ * HTTP 客户端封装：统一超时、请求头、拦截器链。
+ * 基于 @kit.NetworkKit 的 http 模块（Promise 风格）。
+ */
+export class HttpClient {
+  private readonly client: http.HttpRequest = http.createHttp();
+  private interceptors: HttpInterceptor[] = [];
+
+  addInterceptor(interceptor: HttpInterceptor): HttpClient {
+    this.interceptors.push(interceptor);
+    return this;
+  }
+
+  async get(url: string, header?: Record<string, string>): Promise<string> {
+    return this.request(url, http.RequestMethod.GET, undefined, header);
+  }
+
+  async post(url: string, body: string, header?: Record<string, string>): Promise<string> {
+    return this.request(url, http.RequestMethod.POST, body, header);
+  }
+
+  async put(url: string, body: string, header?: Record<string, string>): Promise<string> {
+    return this.request(url, http.RequestMethod.PUT, body, header);
+  }
+
+  async delete(url: string, header?: Record<string, string>): Promise<string> {
+    return this.request(url, http.RequestMethod.DELETE, undefined, header);
+  }
+
+  private async request(url: string, method: http.RequestMethod, body?: string,
+    header?: Record<string, string>): Promise<string> {
+    let headers: Record<string, string> = {};
+    if (header !== undefined) {
+      headers = header;
+    }
+    for (const interceptor of this.interceptors) {
+      headers = interceptor.onRequest(headers);
+    }
+
+    const options: http.HttpRequestOptions = {
+      method: method,
+      header: headers,
+      expectDataType: http.HttpDataType.STRING,
+      connectTimeout: 10000,
+      readTimeout: 10000
+    };
+    if (body !== undefined) {
+      options.extraData = body;
+    }
+
+    try {
+      const response: http.HttpResponse = await this.client.request(url, options);
+      for (const interceptor of this.interceptors) {
+        interceptor.onResponse(response.responseCode, response.result as string);
+      }
+      return response.result as string;
+    } catch (err) {
+      throw ApiError.network(JSON.stringify(err));
+    }
+  }
+}

common/src/main/ets/network/HttpInterceptor.ets

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+/**
+ * 请求/响应拦截器接口。
+ * 实现类可注入请求头（鉴权）、统一处理响应（401/错误码）等。
+ */
+export interface HttpInterceptor {
+  /** 请求发出前，返回（可修改的）请求头。 */
+  onRequest(header: Record<string, string>): Record<string, string>;
+  /** 响应返回后，可据此抛错中断（如 401 触发登出）。 */
+  onResponse(responseCode: number, result: string): void;
+}