Add Docker GUI support with X11 forwarding

Dockerfile

@@ -1,12 +1,19 @@
 FROM python:3.10.14-slim
 
-RUN apt update
-RUN apt-get install -y ffmpeg
-RUN apt install python3-pip -y
+# system deps
+RUN apt update && apt-get install -y \
+    ffmpeg \
+    python3-pip \
+    x11-apps \
+    && rm -rf /var/lib/apt/lists/*
 
-RUN mkdir /app
-ADD . /app
 WORKDIR /app
+COPY . .
+
 RUN pip install -r requirements.txt
 
-CMD ["python3", "main.py"]
+# allow GUI
+ENV DISPLAY=:0
+
+# run GUI instead of CLI
+CMD ["python3", "GUI.py"]