feat: add contact UI helpers and path editor for routing management

- Implemented contactTypeIcon and contactTypeColor functions for better UI representation of contact types.
- Created colorForName and firstCharacterOrEmoji functions to enhance contact display.
- Developed PathEditorSheet widget for managing contact paths with a user-friendly interface.
- Introduced RoutingSheet for managing contact routing modes and displaying path history.
- Added a script for generating proof of concept (PoC) payloads for clipboard contact import validation.

lib/services/message_retry_service.dart

@@ -449,6 +449,11 @@ class MessageRetryService extends ChangeNotifier {
     });
   }
 
+  void untrack(String messageId) {
+    _timeoutTimers[messageId]?.cancel();
+    _cleanupMessage(messageId);
+  }
+
   void _cleanupMessage(String messageId) {
     _moveAckHashesToHistory(messageId);
     _ackHashToMessageId.removeWhere(