fix: Improve message signal chip behavior

lib/utils/link_quality.dart

@@ -0,0 +1,54 @@
+import 'package:flutter/material.dart';
+
+int rssiScore(int rssiDbm) {
+  if (rssiDbm >= -60) return 5;
+  if (rssiDbm >= -70) return 4;
+  if (rssiDbm >= -80) return 3;
+  if (rssiDbm >= -90) return 2;
+  if (rssiDbm >= -100) return 1;
+  return 0;
+}
+
+int snrScore(double snrDb) {
+  if (snrDb >= 10) return 5;
+  if (snrDb >= 5) return 4;
+  if (snrDb >= 0) return 3;
+  if (snrDb >= -5) return 2;
+  if (snrDb >= -10) return 1;
+  return 0;
+}
+
+String linkQualityLabel(int? rssiDbm, double? snrDb) {
+  var totalScore = 0;
+  var metricCount = 0;
+
+  if (rssiDbm != null) {
+    totalScore += rssiScore(rssiDbm);
+    metricCount += 1;
+  }
+  if (snrDb != null) {
+    totalScore += snrScore(snrDb);
+    metricCount += 1;
+  }
+
+  if (metricCount == 0) return 'Weak';
+
+  final averageScore = totalScore / metricCount;
+  if (averageScore >= 4.5) return 'Excellent';
+  if (averageScore >= 3.5) return 'Good';
+  if (averageScore >= 2.5) return 'Fair';
+  return 'Weak';
+}
+
+Color linkQualityColor(String quality) {
+  switch (quality) {
+    case 'Excellent':
+      return Colors.green;
+    case 'Good':
+      return Colors.lightGreen;
+    case 'Fair':
+      return Colors.orange;
+    default:
+      return Colors.redAccent;
+  }
+}