refactor: rename Format to Quality, add container Audio/Video sub-pickers

- Rename 'Format' button to 'Quality' in settings (audio_quality/video_quality)
- Add DefaultAudioContainer and DefaultVideoContainer to UserPreferences
- Container settings now has Audio/Video sub-pickers (mp3/m4a/opus vs mp4/mkv/webm)
- Add migration 003 for new container columns
- Update repo layer and playlist flow for new fields
- Update back routing: back_quality, back_container

internal/handler/playlist.go

@@ -142,16 +142,19 @@ func (h *Handler) handlePlaylistConfirm(ctx context.Context, chatID int64, msgID
 		prefs, prefErr := h.Repo.GetOrCreatePreferences(userID)
 		if prefErr != nil {
 			prefs = &domain.UserPreferences{
-				DefaultMediaType:   domain.MediaTypeVideoAudio,
-				DefaultAudioFormat: "best",
-				DefaultVideoFormat: "best",
-				DefaultContainer:   "mp4",
+				DefaultMediaType:      domain.MediaTypeVideoAudio,
+				DefaultAudioFormat:    "best",
+				DefaultVideoFormat:    "best",
+				DefaultAudioContainer: "mp3",
+				DefaultVideoContainer: "mp4",
 			}
 		}
 
 		formatID := prefs.DefaultVideoFormat
+		container := prefs.DefaultVideoContainer
 		if prefs.DefaultMediaType == domain.MediaTypeAudio {
 			formatID = prefs.DefaultAudioFormat
+			container = prefs.DefaultAudioContainer
 		}
 		format := &domain.Format{ID: formatID}
 		for _, f := range info.Formats {
@@ -168,7 +171,7 @@ func (h *Handler) handlePlaylistConfirm(ctx context.Context, chatID int64, msgID
 			URL:            entry.URL,
 			MediaType:      prefs.DefaultMediaType,
 			SelectedFormat: format,
-			Container:      prefs.DefaultContainer,
+			Container:      container,
 			Language:       prefs.DefaultLanguage,
 			Status:         domain.StatusDownloading,
 			Title:          entry.Title,