fix: add missing logger in downloader.py (startup crash)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

downloader.py

@@ -1,4 +1,5 @@
 import asyncio
+import logging
 import re
 import sqlite3
 import threading
@@ -9,6 +10,8 @@ from pathlib import Path
 
 import yt_dlp
 
+logger = logging.getLogger(__name__)
+
 from arte_api import get_versions, select_lang_tag
 
 OUTPUT_DIR = "/data/Arte"