Refactor Dockerfile to install dependencies with no-install-recommends and update ffmpeg checks in ConfigLoader for improved audio mode handling

Dockerfile

@@ -1,5 +1,17 @@
 FROM python:3.12-slim
+
 WORKDIR /app
-RUN apt-get update && apt-get install -y aria2 ffmpeg yt-dlp
+
+# Install runtime dependencies: aria2, ffmpeg, yt-dlp
+# Use --no-install-recommends to keep image small and clean up apt lists
+RUN apt-get update \
+	&& apt-get install -y --no-install-recommends \
+	   ca-certificates \
+	   aria2 \
+	   ffmpeg \
+	   yt-dlp \
+	&& rm -rf /var/lib/apt/lists/*
+
 COPY yt-playlist-main.py /app/
+
 CMD ["python", "yt-playlist-main.py"]