fix(plex): tolerate malformed activity rows

lib/models/plex/plex_activity.dart

@@ -1,20 +1,23 @@
 import 'package:json_annotation/json_annotation.dart';
 
+import '../../utils/json_utils.dart';
+
 part 'plex_activity.g.dart';
 
 /// Represents a running background task on a Plex Media Server (from /activities endpoint).
 @JsonSerializable(createToJson: false)
 class PlexActivity {
-  @JsonKey(defaultValue: '')
+  @JsonKey(fromJson: stringOrEmpty)
   final String uuid;
-  @JsonKey(defaultValue: '')
+  @JsonKey(fromJson: stringOrEmpty)
   final String type;
-  @JsonKey(defaultValue: '')
+  @JsonKey(fromJson: stringOrEmpty)
   final String title;
+  @JsonKey(readValue: readStringField)
   final String? subtitle;
-  @JsonKey(defaultValue: 0)
+  @JsonKey(fromJson: flexibleIntOrZero)
   final int progress; // 0–100
-  @JsonKey(defaultValue: false)
+  @JsonKey(fromJson: flexibleBool)
   final bool cancellable;
 
   const PlexActivity({

lib/models/plex/plex_activity.g.dart

@@ -7,10 +7,10 @@ part of 'plex_activity.dart';
 // **************************************************************************
 
 PlexActivity _$PlexActivityFromJson(Map<String, dynamic> json) => PlexActivity(
-  uuid: json['uuid'] as String? ?? '',
-  type: json['type'] as String? ?? '',
-  title: json['title'] as String? ?? '',
-  subtitle: json['subtitle'] as String?,
-  progress: (json['progress'] as num?)?.toInt() ?? 0,
-  cancellable: json['cancellable'] as bool? ?? false,
+  uuid: stringOrEmpty(json['uuid']),
+  type: stringOrEmpty(json['type']),
+  title: stringOrEmpty(json['title']),
+  subtitle: readStringField(json, 'subtitle') as String?,
+  progress: flexibleIntOrZero(json['progress']),
+  cancellable: flexibleBool(json['cancellable']),
 );