feat: implement social login functionality with Google, Facebook, and Twitter, including API integration and platform-specific configurations.

lib/features/agents/presentation/screens/agent_detail_screen.dart

@@ -308,6 +308,13 @@ class _AgentDetailScreenState extends ConsumerState<AgentDetailScreen> {
       if (!mounted) return;
       if (conversationId != null) {
         context.push('/messages/chat/$conversationId');
+      } else {
+        ScaffoldMessenger.of(context).showSnackBar(
+          const SnackBar(
+            content: Text('You need to be connected to send messages.'),
+            behavior: SnackBarBehavior.floating,
+          ),
+        );
       }
     } finally {
       if (mounted) setState(() => _isStartingConversation = false);