- Pass app logger to yt-dlp so internal [download] progress lines
are routed through the INFO-level logger instead of stdout.
- Throttle download_progress_handler debug logging to avoid
flooding logs on every fragment tick.
- Switch key provider lifecycle messages to INFO (start/complete)
while keeping verbose details at DEBUG.
- Set debug_enabled=False in development config so dev mode
does not emit extra debug noise.
- Update config docstring example from DEBUG to INFO.
