feat(message): support media attachments in outbound tool

pkg/channels/feishu/feishu_64.go

@@ -497,10 +497,18 @@ func (c *FeishuChannel) SendMedia(ctx context.Context, msg bus.OutboundMediaMess
 		return nil, fmt.Errorf("no media store available: %w", channels.ErrSendFailed)
 	}
 
+	caption := firstMediaCaption(msg.Parts)
+	sentAny := false
 	for _, part := range msg.Parts {
 		if err := c.sendMediaPart(ctx, msg.ChatID, part, store); err != nil {
 			return nil, err
 		}
+		sentAny = true
+	}
+	if sentAny && caption != "" {
+		if _, err := c.sendText(ctx, msg.ChatID, caption); err != nil {
+			return nil, err
+		}
 	}
 
 	if hasTrackedMsg {
@@ -557,6 +565,15 @@ func (c *FeishuChannel) sendMediaPart(
 	return nil
 }
 
+func firstMediaCaption(parts []bus.MediaPart) string {
+	for _, part := range parts {
+		if caption := strings.TrimSpace(part.Caption); caption != "" {
+			return caption
+		}
+	}
+	return ""
+}
+
 // --- Inbound message handling ---
 
 func (c *FeishuChannel) handleMessageReceive(ctx context.Context, event *larkim.P2MessageReceiveV1) error {