fix: resolve flutter analyze errors - remove leaked code, fix method calls, cleanup imports

lib/core/models/comment_model.dart

@@ -0,0 +1,37 @@
+import 'package:equatable/equatable.dart';
+
+class CommentModel extends Equatable {
+  const CommentModel({
+    required this.id,
+    required this.userId,
+    required this.username,
+    required this.novelId,
+    required this.content,
+    required this.createdAt,
+    this.avatarUrl,
+    this.chapterId,
+  });
+
+  final String id;
+  final String userId;
+  final String username;
+  final String novelId;
+  final String content;
+  final DateTime createdAt;
+  final String? avatarUrl;
+  final String? chapterId;
+
+  factory CommentModel.fromJson(Map<String, dynamic> json) => CommentModel(
+        id: json['id'] as String,
+        userId: json['userId'] as String,
+        username: json['username'] as String? ?? 'User',
+        novelId: json['novelId'] as String,
+        content: json['content'] as String,
+        createdAt: DateTime.parse(json['createdAt'] as String),
+        avatarUrl: json['avatarUrl'] as String?,
+        chapterId: json['chapterId'] as String?,
+      );
+
+  @override
+  List<Object?> get props => [id];
+}