feat: MeshCore SAR - Flutter BLE mesh radio companion app

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/models/advert_location.dart

@@ -0,0 +1,40 @@
+import 'package:latlong2/latlong.dart';
+
+/// Single advertisement location point in a contact's movement history
+class AdvertLocation {
+  final LatLng location;
+  final DateTime timestamp;
+
+  AdvertLocation({
+    required this.location,
+    required this.timestamp,
+  });
+
+  /// Get friendly time ago display
+  String get timeAgo {
+    final diff = DateTime.now().difference(timestamp);
+    if (diff.inMinutes < 1) return 'Just now';
+    if (diff.inMinutes < 60) return '${diff.inMinutes}m ago';
+    if (diff.inHours < 24) return '${diff.inHours}h ago';
+    return '${diff.inDays}d ago';
+  }
+
+  @override
+  String toString() {
+    return 'AdvertLocation(lat: ${location.latitude.toStringAsFixed(6)}, '
+           'lon: ${location.longitude.toStringAsFixed(6)}, '
+           'time: ${timestamp.toIso8601String()})';
+  }
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(this, other)) return true;
+    return other is AdvertLocation &&
+           other.location.latitude == location.latitude &&
+           other.location.longitude == location.longitude &&
+           other.timestamp == timestamp;
+  }
+
+  @override
+  int get hashCode => Object.hash(location.latitude, location.longitude, timestamp);
+}