Add VPN session monitoring service

lib/services/vpn_session_service.dart

@@ -0,0 +1,35 @@
+import 'package:supabase/supabase.dart';
+import 'package:waylume_server/config/supabase_config.dart';
+
+class VpnSessionService {
+  
+  /// Detects existing VPN sessions for this server and prints their IDs
+  static Future<void> detectSessions() async {
+    try {
+      final serverId = fromEnivronment('SERVER_ID');
+      
+      if (serverId == null) {
+        print('ERROR: SERVER_ID environment variable not set');
+        return;
+      }
+      
+      // Get all sessions for this server
+      final sessions = await SUPABASE_CLIENT
+          .from('vpn_sessions')
+          .select('id')
+          .eq('server_id', serverId);
+      
+      if (sessions.isEmpty) {
+        print('No VPN sessions found for server: $serverId');
+      } else {
+        print('Found ${sessions.length} VPN sessions for server: $serverId');
+        for (final session in sessions) {
+          print('Session ID: ${session['id']}');
+        }
+      }
+      
+    } catch (e) {
+      print('Error detecting sessions: $e');
+    }
+  }
+}