Added a basic neighbours screen for repeaters

lib/widgets/snr_indicator.dart

@@ -0,0 +1,62 @@
+import 'package:flutter/material.dart';
+
+List<double> getSNRfromSF(int spreadingFactor) {
+  switch (spreadingFactor) {
+    case 7:
+      return [4.0, -2.0, -4.0, -6.0];
+    case 8:
+      return [4.0, -4.0, -6.0, -8.0];
+    case 9:
+      return [4.0, -6.0, -8.0, -10.0];
+    case 10:
+      return [4.0, -8.0, -10.0, -13.0];
+    case 11:
+      return [4.0, -10.0, -12.5, -15.0];
+    case 12:
+      return [4.0, -12.5, -15.0, -18.0];
+    default:
+      return []; // Or throw Exception('Invalid SF: $spreadingFactor');
+  }
+}
+
+class SNRIcon extends StatelessWidget {
+  final double snr;
+  final List<double> snrLevels;
+
+  const SNRIcon({
+    super.key,
+    required this.snr,
+    this.snrLevels = const [4.0, -2.0, -4.0, -6.0],
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    IconData icon;
+    Color color;
+
+    if (snr >= snrLevels[0]) {
+      icon = Icons.signal_cellular_alt;
+      color = Colors.green;
+    } else if (snr >= snrLevels[1]) {
+      icon = Icons.signal_cellular_alt;
+      color = Colors.lightGreen;
+    } else if (snr >= snrLevels[2]) {
+      icon = Icons.signal_cellular_alt;
+      color = Colors.yellow;
+    } else if (snr >= snrLevels[3]) {
+      icon = Icons.signal_cellular_alt_2_bar;
+      color = Colors.orange;
+    } else {
+      icon = Icons.signal_cellular_alt_1_bar;
+      color = Colors.red;
+    }
+
+    return Column(
+      mainAxisAlignment: MainAxisAlignment.center,
+      children: [
+        Icon(icon, color: color),
+        Text('$snr dB', style: TextStyle(fontSize: 10, color: color)),
+      ],
+    );
+  }
+}