reimplement location aware snr-indikator after alpha7

lib/utils/contact_search.dart

@@ -1,3 +1,6 @@
+import 'package:latlong2/latlong.dart';
+
+import '../connector/meshcore_protocol.dart';
 import '../models/contact.dart';
 
 export 'contact_filter_types.dart';
@@ -43,3 +46,55 @@ String? _extractHexPrefix(String query) {
   if (!RegExp(r'^[0-9a-f]+$').hasMatch(cleaned)) return null;
   return cleaned;
 }
+
+Contact? getRepeaterPrefixMatchNearLocation(
+  List<Contact> contacts,
+  int pubkeyFirstByte, {
+  LatLng? searchPoint,
+  bool preferFavorites = false,
+}) {
+  final candidates = contacts
+      .where(
+        (c) =>
+            c.publicKey.isNotEmpty &&
+            c.publicKey.first == pubkeyFirstByte &&
+            (c.type == advTypeRepeater || c.type == advTypeRoom),
+      )
+      .toList();
+
+  if (candidates.isEmpty) return null;
+
+  candidates.sort((a, b) {
+    if (preferFavorites) {
+      final favA = a.isFavorite ? 1 : 0;
+      final favB = b.isFavorite ? 1 : 0;
+      final favCompare = favB.compareTo(favA);
+      if (favCompare != 0) return favCompare;
+    }
+
+    final seenCompare = b.lastSeen.compareTo(a.lastSeen);
+    if (seenCompare != 0) return seenCompare;
+
+    return a.publicKeyHex.compareTo(b.publicKeyHex);
+  });
+
+  if (searchPoint == null) {
+    return candidates.first;
+  }
+
+  final distance = Distance();
+  Contact best = candidates.first;
+  var bestDistance = double.infinity;
+
+  for (final c in candidates) {
+    if (c.hasLocation) {
+      final d = distance(searchPoint, LatLng(c.latitude!, c.longitude!));
+      if (d < bestDistance) {
+        bestDistance = d;
+        best = c;
+      }
+    }
+  }
+
+  return best;
+}