feat: Enhance drawing functionality with sender tracking and sharing capabilities

lib/utils/drawing_message_parser.dart

@@ -0,0 +1,42 @@
+import 'dart:convert';
+import '../models/map_drawing.dart';
+
+/// Parser for drawing messages transmitted over mesh network
+class DrawingMessageParser {
+  /// Drawing message prefix
+  static const String prefix = 'D:';
+
+  /// Check if message is a drawing message
+  static bool isDrawingMessage(String text) {
+    return text.startsWith(prefix);
+  }
+
+  /// Parse drawing message text into MapDrawing object
+  /// Returns null if parsing fails
+  static MapDrawing? parseDrawingMessage(String text) {
+    if (!isDrawingMessage(text)) {
+      return null;
+    }
+
+    try {
+      // Remove prefix
+      final jsonStr = text.substring(prefix.length);
+
+      // Parse JSON
+      final json = jsonDecode(jsonStr) as Map<String, dynamic>;
+
+      // Use existing fromJson method
+      return MapDrawing.fromJson(json);
+    } catch (e) {
+      return null;
+    }
+  }
+
+  /// Create drawing message text from MapDrawing object
+  /// Includes sender name in the message
+  static String createDrawingMessage(MapDrawing drawing, String senderName) {
+    final json = drawing.toNetworkJson(senderName);
+    final jsonStr = jsonEncode(json);
+    return '$prefix$jsonStr';
+  }
+}