Fix: Add Hugging Face Spaces user requirements

- Add user creation with UID 1000 (required by HF Spaces)
- Set proper HOME and PATH environment variables
- Copy files with correct ownership (--chown=user)
- Run application as non-root user

Follows Hugging Face Docker Spaces best practices:
https://huggingface.co/docs/hub/spaces-sdks-docker

Dockerfile

@@ -3,28 +3,39 @@
 
 FROM python:3.12-slim
 
-# Set working directory
-WORKDIR /app
-
 # Set environment variables
 ENV PYTHONUNBUFFERED=1 \
     PYTHONDONTWRITEBYTECODE=1 \
     PORT=7860
 
-# Install system dependencies
+# The two following lines are required for Hugging Face Spaces Dev Mode
+# See: https://huggingface.co/docs/hub/spaces-sdks-docker
+RUN useradd -m -u 1000 user
+USER user
+
+# Set home to the user's home directory
+ENV HOME=/home/user \
+    PATH=/home/user/.local/bin:$PATH
+
+# Set working directory
+WORKDIR /app
+
+# Install system dependencies (as root, then switch back to user)
+USER root
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
         gcc \
         && rm -rf /var/lib/apt/lists/*
+USER user
 
 # Copy requirements first for better Docker layer caching
-COPY requirements.txt .
+COPY --chown=user requirements.txt .
 
 # Install Python dependencies
 RUN pip install --no-cache-dir -r requirements.txt
 
 # Copy project files
-COPY . .
+COPY --chown=user . .
 
 # Install the package in editable mode
 RUN pip install --no-cache-dir -e .
@@ -32,9 +43,5 @@ RUN pip install --no-cache-dir -e .
 # Expose Hugging Face Spaces default port
 EXPOSE 7860
 
-# Health check endpoint
-HEALTHCHECK --interval=30s --timeout=10s --start-period=5s --retries=3 \
-    CMD python -c "import urllib.request; urllib.request.urlopen('http://localhost:7860/').read()"
-
 # Run the FastAPI application with uvicorn
 CMD ["uvicorn", "web.app:app", "--host", "0.0.0.0", "--port", "7860"]