Simplify path removal logic and clean up unused imports in path management dialog

lib/screens/map_screen.dart

@@ -2165,9 +2165,7 @@ class _MapScreenState extends State<MapScreen> {
 
   void _removePath() {
     setState(() {
-      _pathTraceContacts.remove(
-        _pathTrace.last,
-      ); // Remove last contact from path trace
+      _pathTraceContacts.removeLast();
       _pathTrace.removeLast(); // Remove last node from path trace
       _points.removeLast(); // Remove last point from points list
       _polylines.clear(); // Clear polylines

lib/widgets/path_management_dialog.dart

@@ -1,7 +1,6 @@
 import 'dart:typed_data';
 
 import 'package:flutter/material.dart';
-import 'package:meshcore_open/connector/meshcore_protocol.dart';
 import 'package:meshcore_open/models/path_history.dart';
 import 'package:meshcore_open/screens/path_trace_map.dart';
 import 'package:meshcore_open/widgets/elements_ui.dart';