chore: Fix dart deprecation messages

lib/util/color_extensions.dart

@@ -2,6 +2,37 @@ import 'package:flutter/material.dart';
 
 import 'package:fladder/util/localization_helper.dart';
 
+Color? colorFromJson(dynamic color) {
+  if (color == null) return null;
+
+  if (color is Map<String, dynamic>) {
+    return Color.from(
+      alpha: color['alpha'] ?? 1.0,
+      red: color['red'] ?? 1.0,
+      green: color['green'] ?? 1.0,
+      blue: color['blue'] ?? 1.0,
+    );
+  }
+
+  // Deprecated format (integer value)
+  if (color is int) {
+    return Color(color);
+  }
+
+  return null;
+}
+
+extension ColorExtensions on Color {
+  Map<String, dynamic> get toMap {
+    return {
+      'alpha': a,
+      'red': r,
+      'green': g,
+      'blue': b,
+    };
+  }
+}
+
 extension DynamicSchemeVariantExtension on DynamicSchemeVariant {
   String label(BuildContext context) => switch (this) {
         DynamicSchemeVariant.tonalSpot => context.localized.schemeSettingsTonalSpot,