feat: add DRM search-by-name fallback for individual Spotify tracks

When SearchYoutube with the Spotify URL fails for individual tracks,
offer a 'Search on YouTube' button that lets the user enter a search
query (artist/song name) to find the content on YouTube.

internal/handler/download.go

@@ -70,7 +70,15 @@ func (h *Handler) handleURLInput(ctx context.Context, chatID int64, text string,
 		if strings.Contains(errMsg, "DRM") {
 			youtubeURL, ytTitle, searchErr := h.YtDlp.SearchYoutube(text)
 			if searchErr != nil {
-				h.sendText(ctx, chatID, fmt.Sprintf("This content is DRM protected and no YouTube alternative was found: %s", errMsg))
+				kb := models.InlineKeyboardMarkup{
+					InlineKeyboard: [][]models.InlineKeyboardButton{
+						{{Text: "Search on YouTube", CallbackData: "drm_search"}},
+						{{Text: "Cancel", CallbackData: "pending_cancel"}},
+					},
+				}
+				h.Bot.SendMessage(ctx, &tgbot.SendMessageParams{
+					ChatID: chatID, Text: "This content is DRM protected and no YouTube alternative was found automatically. Try searching by name:", ReplyMarkup: kb,
+				})
 				return
 			}
 			h.sendText(ctx, chatID, fmt.Sprintf("This content is DRM protected. Found on YouTube: %s", ytTitle))