refactor: 重命名 API 文件并更新引用路径

- 重命名 13 个 API 文件，去掉 -api 后缀
  * src/api/auth-api.ts  auth.ts
  * src/api/codegen-api.ts  codegen.ts
  * src/api/file-api.ts  file.ts
  * src/api/system/*.ts (9个文件)

- 批量更新 50+ 处 API 引用路径
- 修复 websocket 和枚举导入路径
- 确保零编码问题（使用 UTF-8 编码）

src/views/profile/index.vue

@@ -230,9 +230,9 @@ import UserAPI, {
   MobileUpdateForm,
   EmailUpdateForm,
   UserProfileForm,
-} from "@/api/system/user-api";
+} from "@/api/system/user";
 
-import FileAPI from "@/api/file-api";
+import FileAPI from "@/api/file";
 import { useUserStoreHook } from "@/store";
 
 import { Camera } from "@element-plus/icons-vue";

src/views/profile/notice/index.vue

@@ -119,7 +119,7 @@ import NoticeAPI, {
   type NoticePageVO,
   type NoticePageQuery,
   type NoticeDetailVO,
-} from "@/api/system/notice-api";
+} from "@/api/system/notice";
 
 const queryFormRef = ref();
 const pageData = ref<NoticePageVO[]>([]);