Fix Dockerfile: add non-root user for HF Spaces

Dockerfile

@@ -1,5 +1,7 @@
 FROM python:3.11-slim
 
+RUN useradd -m -u 1000 user
+
 WORKDIR /app
 
 COPY requirements.txt .
@@ -7,7 +9,11 @@ RUN pip install --no-cache-dir -r requirements.txt
 
 COPY . .
 
+RUN chown -R user:user /app
+USER user
+
 ENV PYTHONPATH=/app
+ENV HOME=/home/user
 
 EXPOSE 7860