fix: use article link as post body for RSS posts, card shows title

go-backend/internal/services/official_accounts_service.go

@@ -474,8 +474,8 @@ func (s *OfficialAccountsService) PostNextArticle(ctx context.Context, configID
 	var body string
 	switch cfg.AccountType {
 	case "rss":
-		// Post the title — the link preview card handles the URL display
-		body = art.Title
+		// Post the link — renders as small clickable text; the link preview card shows the title/description
+		body = art.Link
 	case "news":
 		// Generate AI commentary
 		rssItem := &RSSItem{