feat: add auto-select from preferences and type picker

- Add MediaTypeAsk (0) as the default, mapping old video_audio to Ask
- Show Video/Audio/Ask type picker when no default media type is set
- Auto-select matching format and skip picker when defaults are configured
- Add autoSelectVideoFormat / autoSelectAudioFormat helpers with closest-match
- Add buildFilteredFormatList for type-filtered format lists
- Add Media Type setting in settings UI (Ask/Video/Audio)
- Add --merge-output-format mp4 for video downloads via yt-dlp
- Fix formatLabelForDisplay to show Height fallback and Extension
- Add cookies volume mount to docker-compose.yml
- Document cookies setup and new features in README

internal/handler/handler.go

@@ -273,6 +273,8 @@ func (h *Handler) routePrefixedCallback(ctx context.Context, chatID int64, msgID
 	defer h.answerCb(ctx, cbID)
 
 	switch {
+	case strings.HasPrefix(data, "type_"):
+		h.handleTypeSelection(ctx, chatID, msgID, userID, data[5:])
 	case strings.HasPrefix(data, "format_"):
 		h.handleFormatSelection(ctx, chatID, msgID, userID, data[7:])
 	case strings.HasPrefix(data, "secondary_"):