上传视频时，请求obs生成封面

lib/data/repositories/message/upload_file.dart

+import 'dart:convert';
 import 'dart:io';
 
 import 'package:appframe/config/constant.dart';
@@ -188,9 +189,9 @@ class UploadFileHandler extends MessageHandler {
     ///
     /// 8 针对视频生成封面
     ///
-    // if (mimeType?.startsWith('video/') ?? false) {
-    //   await _genHwVideoCover(dio, objectKey);
-    // }
+    if (mimeType?.startsWith('video/') ?? false) {
+      await _genHwVideoCover(dio, objectKey);
+    }
 
     dio.close(force: true);
     bxeApiService.close();
@@ -334,15 +335,16 @@ class UploadFileHandler extends MessageHandler {
         "api-key": 'FJ9qv53Bxp',
       };
       var params = {
-        "videoKeys": keys,
+        "videoKeys": [keys],
         "outputSuffix": "_p1",
       };
       await dio.post(
         '$_genBaseUrl/go/mpc/create_covers',
-        data: params,
+        data: jsonEncode(params),
         options: Options(
           headers: headers,
           contentType: 'application/json',
+          responseType: ResponseType.json,
         ),
       );
     } catch (e) {