refactor: 重构 API 层目录结构 & 样式模块化拆分

- API 层按业务域拆分（api/auth/, api/file/, api/system/*）
- 类型定义从 types/api/ 移入对应 api 模块内（就近原则）
- 公共类型统一为 api/common.ts，移除冗余类型重导出
- 样式文件按职责拆分（base/, layout/, vendors/），移除 common.scss
- 移除失效的单元测试文件

src/api/auth/index.ts

@@ -0,0 +1,69 @@
+import request from "@/utils/request";
+import type { LoginRequest, LoginResponse, CaptchaInfo } from "./types";
+
+const AUTH_BASE_URL = "/api/v1/auth";
+
+const AuthAPI = {
+  /** 登录接口*/
+  login(data: LoginRequest) {
+    const payload: Record<string, any> = {
+      username: data.username,
+      password: data.password,
+      captchaId: data.captchaId,
+      captchaCode: data.captchaCode,
+    };
+
+    // tenantId 可选，仅在提供时包含（多租户功能）
+    if (typeof data.tenantId !== "undefined") {
+      payload.tenantId = data.tenantId;
+    }
+
+    return request<any, LoginResponse>({
+      url: `${AUTH_BASE_URL}/login`,
+      method: "post",
+      data: payload,
+    });
+  },
+
+  /** 切换租户(平台用户) - 返回新的 token */
+  switchTenant(tenantId: number) {
+    return request<any, LoginResponse>({
+      url: `${AUTH_BASE_URL}/switch-tenant`,
+      method: "post",
+      params: { tenantId },
+    });
+  },
+
+  /** 刷新 token 接口*/
+  refreshToken(refreshToken: string) {
+    return request<any, LoginResponse>({
+      url: `${AUTH_BASE_URL}/refresh-token`,
+      method: "post",
+      params: { refreshToken },
+      headers: {
+        Authorization: "no-auth",
+      },
+    });
+  },
+
+  /** 退出登录接口 */
+  logout() {
+    return request({
+      url: `${AUTH_BASE_URL}/logout`,
+      method: "delete",
+    });
+  },
+
+  /** 获取验证码接口*/
+  getCaptcha() {
+    return request<any, CaptchaInfo>({
+      url: `${AUTH_BASE_URL}/captcha`,
+      method: "get",
+    });
+  },
+};
+
+export default AuthAPI;
+
+// 重导出类型
+export * from "./types";