claude refactorings, flutter best practices, platform dependent changes, general cleanup

lib/widget/debug/json_viewer.dart

@@ -1,6 +1,7 @@
+import 'dart:convert';
+
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
-import 'package:pretty_json/pretty_json.dart';
 
 class JsonViewer extends StatelessWidget {
   final String title;
@@ -19,7 +20,9 @@ class JsonViewer extends StatelessWidget {
       ),
     );
   
-  static String format(Map<String, dynamic> jsonInput) => prettyJson(jsonInput, indent: 2);
+  static final _encoder = const JsonEncoder.withIndent('  ');
+
+  static String format(Map<String, dynamic> jsonInput) => _encoder.convert(jsonInput);
 
   static void asDialog(BuildContext context, Map<String, dynamic> dataMap) {
     showDialog(context: context, builder: (context) => AlertDialog(