Enhance message handling in OpenAI adapter to skip non-delta "done" messages

- Added logic to ignore "done" messages that are not delta updates, ensuring that final confirmation messages are not sent to OpenAI clients, which rely on finish_reason instead.

agent/output/adapters/openai/adapter.go

@@ -68,6 +68,13 @@ func (a *Adapter) Adapt(msg *message.Message) ([]interface{}, error) {
 		return []interface{}{}, nil // Return empty array, nothing to send
 	}
 
+	// Skip "done" messages that are not delta updates
+	// These are final confirmation messages for CUI clients
+	// OpenAI clients don't need them - they use finish_reason instead
+	if msg.Done && !msg.Delta {
+		return []interface{}{}, nil // Return empty array, nothing to send
+	}
+
 	// Get converter for this message type
 	converter, exists := a.registry.GetConverter(msg.Type)
 	if !exists {