feat: Add localization support for contact and SAR marker display names

lib/models/contact.dart

@@ -4,6 +4,7 @@ import 'package:latlong2/latlong.dart';
 import 'package:flutter/material.dart';
 import 'contact_telemetry.dart';
 import 'advert_location.dart';
+import '../l10n/app_localizations.dart';
 
 /// MeshCore contact types
 enum ContactType {
@@ -213,6 +214,16 @@ class Contact {
     return advName.substring(emoji.length).trim();
   }
 
+  /// Get localized display name (for Public Channel and other special contacts)
+  String getLocalizedDisplayName(BuildContext context) {
+    // Check if this is the Public Channel (all-zeros public key)
+    if (publicKeyHex == '0000000000000000000000000000000000000000000000000000000000000000') {
+      return AppLocalizations.of(context)!.publicChannel;
+    }
+    // For all other contacts, use the regular display name
+    return displayName;
+  }
+
   /// Check if contact has a learned routing path
   /// When true, messages will use direct routing. When false, messages will use flood mode.
   bool get hasPath => outPathLen > 0 && outPathLen <= 64;

lib/models/sar_marker.dart

@@ -1,5 +1,7 @@
 import 'dart:typed_data';
+import 'package:flutter/material.dart';
 import 'package:latlong2/latlong.dart';
+import '../l10n/app_localizations.dart';
 
 /// SAR (Search & Rescue) marker types
 enum SarMarkerType {
@@ -13,6 +15,23 @@ enum SarMarkerType {
   final String emoji;
   final String displayName;
 
+  /// Get localized display name
+  String getLocalizedName(BuildContext context) {
+    final l10n = AppLocalizations.of(context)!;
+    switch (this) {
+      case SarMarkerType.foundPerson:
+        return l10n.sarMarkerFoundPerson;
+      case SarMarkerType.fire:
+        return l10n.sarMarkerFire;
+      case SarMarkerType.stagingArea:
+        return l10n.sarMarkerStagingArea;
+      case SarMarkerType.object:
+        return l10n.sarMarkerObject;
+      case SarMarkerType.unknown:
+        return 'Unknown';
+    }
+  }
+
   static SarMarkerType fromEmoji(String emoji) {
     switch (emoji) {
       case '🧑':