feat(player): 进度条拖动预览改用雪碧图

lib/core/data/models/drama.dart

@@ -17,6 +17,7 @@ class Episode {
     this.locked = false,
     this.likeCount,
     this.commentCount,
+    this.thumbnailsUrl,
   });
 
   final String id;
@@ -32,19 +33,25 @@ class Episode {
   final bool locked;
   final int? likeCount;
   final int? commentCount;
+  final String? thumbnailsUrl;
 
-  Episode withVideoUrl(String url, {int? likeCount, int? commentCount}) =>
-      Episode(
-        id: id,
-        number: number,
-        title: title,
-        isFree: isFree,
-        videoUrl: url,
-        durationSec: durationSec,
-        locked: locked,
-        likeCount: likeCount ?? this.likeCount,
-        commentCount: commentCount ?? this.commentCount,
-      );
+  Episode withVideoUrl(
+    String url, {
+    int? likeCount,
+    int? commentCount,
+    String? thumbnailsUrl,
+  }) => Episode(
+    id: id,
+    number: number,
+    title: title,
+    isFree: isFree,
+    videoUrl: url,
+    durationSec: durationSec,
+    locked: locked,
+    likeCount: likeCount ?? this.likeCount,
+    commentCount: commentCount ?? this.commentCount,
+    thumbnailsUrl: thumbnailsUrl ?? this.thumbnailsUrl,
+  );
 
   factory Episode.fromJson(Map<String, dynamic> json) {
     return Episode(
@@ -57,6 +64,7 @@ class Episode {
       videoUrl: json['playUrl'] as String? ?? '',
       likeCount: _optionalInt(json['likeCount']),
       commentCount: _optionalInt(json['commentCount']),
+      thumbnailsUrl: _optionalString(json['thumbnailsUrl']),
     );
   }
 }
@@ -159,3 +167,8 @@ class Drama {
 }
 
 int? _optionalInt(dynamic value) => value == null ? null : jsonToInt(value);
+
+String? _optionalString(dynamic value) {
+  final text = value is String ? value.trim() : '';
+  return text.isEmpty ? null : text;
+}