fix: correct location validation and clean up target contact handling

- Fix asymmetric lat/lon validation in _handleContactAdvert (was checking
  longitude != 0 for latitude; now uses (latitude != 0 || longitude != 0)
  for both)
- Remove duplicate targetGuessed assignment in path_trace_map
- Rename public target field to private _targetContact, use local variable
  to avoid unnecessary null-aware operators

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lib/connector/meshcore_connector.dart

@@ -4757,14 +4757,14 @@ class MeshCoreConnector extends ChangeNotifier {
             hasLocation &&
                 latitude != null &&
                 latitude.abs() <= 90 &&
-                longitude != 0
+                (latitude != 0 || longitude != 0)
             ? latitude
             : existing.latitude,
         longitude:
             hasLocation &&
                 longitude != null &&
                 longitude.abs() <= 180 &&
-                longitude != 0
+                (latitude != 0 || longitude != 0)
             ? longitude
             : existing.longitude,
         name: hasName ? name : existing.name,

lib/screens/path_trace_map.dart

@@ -93,7 +93,7 @@ class _PathTraceMapScreenState extends State<PathTraceMapScreen> {
   ValueKey<String> _mapKey = const ValueKey('initial');
   double _pathDistanceMeters = 0.0;
   bool _showNodeLabels = true;
-  Contact? target;
+  Contact? _targetContact;
 
   String _formatPathPrefixes(Uint8List pathBytes) {
     return pathBytes
@@ -305,11 +305,12 @@ class _PathTraceMapScreenState extends State<PathTraceMapScreen> {
         // Compute endpoint position for the target contact.
         LatLng? targetPos;
         bool targetGuessed = false;
-        target = widget.targetContact;
+        _targetContact = widget.targetContact;
 
-        if (target != null) {
-          if (target?.hasLocation ?? false) {
-            targetPos = LatLng(target!.latitude!, target!.longitude!);
+        if (_targetContact != null) {
+          final tc = _targetContact!;
+          if (tc.hasLocation) {
+            targetPos = LatLng(tc.latitude!, tc.longitude!);
           } else if (widget.path.length > 1) {
             // Infer from the last hop: average GPS contacts sharing that hop.
             // For a round-trip path (flipPathAround/reversePathAround), the target-side hop
@@ -334,7 +335,7 @@ class _PathTraceMapScreenState extends State<PathTraceMapScreen> {
                   peers.map((c) => c.longitude!).reduce((a, b) => a + b) /
                   peers.length;
               const offsetDeg = 0.003;
-              final angle = (target!.publicKey[1] / 255.0) * 2 * pi;
+              final angle = (tc.publicKey[1] / 255.0) * 2 * pi;
               targetPos = LatLng(
                 lat + offsetDeg * cos(angle),
                 lon + offsetDeg * sin(angle),
@@ -344,7 +345,7 @@ class _PathTraceMapScreenState extends State<PathTraceMapScreen> {
               final lat = inferredPositions[lastHop]!.latitude;
               final lon = inferredPositions[lastHop]!.longitude;
               const offsetDeg = 0.003;
-              final angle = (target!.publicKey[1] / 255.0) * 2 * pi;
+              final angle = (tc.publicKey[1] / 255.0) * 2 * pi;
               targetPos = LatLng(
                 lat + offsetDeg * cos(angle),
                 lon + offsetDeg * sin(angle),
@@ -355,7 +356,7 @@ class _PathTraceMapScreenState extends State<PathTraceMapScreen> {
               final contact = pathContacts[lastHop];
               if (contact != null && contact.hasLocation) {
                 const offsetDeg = 0.003;
-                final angle = (target!.publicKey[1] / 255.0) * 2 * pi;
+                final angle = (tc.publicKey[1] / 255.0) * 2 * pi;
                 targetPos = LatLng(
                   contact.latitude! + offsetDeg * cos(angle),
                   contact.longitude! + offsetDeg * sin(angle),
@@ -387,7 +388,7 @@ class _PathTraceMapScreenState extends State<PathTraceMapScreen> {
           hopLast = hop;
         }
         if (targetPos != null) {
-          if (target != null && target!.type == advTypeChat) {
+          if (_targetContact != null && _targetContact!.type == advTypeChat) {
             _points.add(targetPos);
           }
         }
@@ -479,7 +480,8 @@ class _PathTraceMapScreenState extends State<PathTraceMapScreen> {
                       ],
                     ),
                   ),
-                if (_hasData) _buildMapPathTrace(context, tileCache, target),
+                if (_hasData)
+                  _buildMapPathTrace(context, tileCache, _targetContact),
                 if (_points.isEmpty &&
                     !_hasData &&
                     !_isLoading &&