Fix permissions: use non-root user and pre-create directories

Dockerfile

@@ -1,19 +1,30 @@
 FROM python:3.11-slim
 
-WORKDIR /app
+# Create non-root user for security
+RUN useradd -m -u 1000 user
+USER user
+ENV HOME=/home/user \
+    PATH=/home/user/.local/bin:$PATH
 
-# Install system dependencies
+WORKDIR $HOME/app
+
+# Install system dependencies as root, then switch back to user
+USER root
 RUN apt-get update && apt-get install -y \
     gcc \
     g++ \
     && rm -rf /var/lib/apt/lists/*
+USER user
 
 # Copy requirements and install Python dependencies
-COPY requirements.txt .
-RUN pip install --no-cache-dir -r requirements.txt
+COPY --chown=user requirements.txt .
+RUN pip install --user --no-cache-dir -r requirements.txt
 
 # Copy application code
-COPY . .
+COPY --chown=user . .
+
+# Create necessary directories with proper permissions
+RUN mkdir -p $HOME/app/.files $HOME/app/.chainlit
 
 # Expose port for Hugging Face Spaces
 EXPOSE 7860