Add peer creation time tracking and enhance DEAD peer handling

lib/wireguard/peers.dart

@@ -69,6 +69,9 @@ Future<WireGuardPeer> createPeer() async {
   // Add peer to WireGuard
   await Process.run('wg', ['set', 'wg0', 'peer', publicKey.trim(), 'allowed-ips', '$ip/32']);
 
+  // Track peer creation time
+  await _trackPeerCreation(publicKey.trim());
+
   return WireGuardPeer(
     privateKey: privateKey,
     publicKey: publicKey.trim(),
@@ -83,6 +86,10 @@ Future<bool> deletePeer(String publicKey) async {
     print('Error removing peer: ${result.stderr}');
     return false;
   }
+  
+  // Clean up peer creation tracking
+  await _cleanupPeerCreation(publicKey);
+  
   return true;
 }
 
@@ -134,3 +141,56 @@ Future<String> _getNextIP() async {
   }
   throw Exception('No available IPs');
 }
+
+/// Tracks when a peer was created
+Future<void> _trackPeerCreation(String publicKey) async {
+  try {
+    final file = File('/tmp/peer_creation_times.json');
+    Map<String, dynamic> creationTimes = {};
+    
+    if (await file.exists()) {
+      final content = await file.readAsString();
+      creationTimes = jsonDecode(content);
+    }
+    
+    creationTimes[publicKey] = DateTime.now().millisecondsSinceEpoch;
+    await file.writeAsString(jsonEncode(creationTimes));
+  } catch (e) {
+    print('Error tracking peer creation: $e');
+  }
+}
+
+/// Gets the creation time for a peer
+Future<DateTime?> getPeerCreationTime(String publicKey) async {
+  try {
+    final file = File('/tmp/peer_creation_times.json');
+    if (!await file.exists()) return null;
+    
+    final content = await file.readAsString();
+    final creationTimes = jsonDecode(content) as Map<String, dynamic>;
+    
+    final timestamp = creationTimes[publicKey];
+    if (timestamp == null) return null;
+    
+    return DateTime.fromMillisecondsSinceEpoch(timestamp);
+  } catch (e) {
+    print('Error getting peer creation time: $e');
+    return null;
+  }
+}
+
+/// Cleans up peer creation tracking when peer is deleted
+Future<void> _cleanupPeerCreation(String publicKey) async {
+  try {
+    final file = File('/tmp/peer_creation_times.json');
+    if (!await file.exists()) return;
+    
+    final content = await file.readAsString();
+    final creationTimes = jsonDecode(content) as Map<String, dynamic>;
+    
+    creationTimes.remove(publicKey);
+    await file.writeAsString(jsonEncode(creationTimes));
+  } catch (e) {
+    print('Error cleaning up peer creation tracking: $e');
+  }
+}