Add Dockerfile and switch HF Space config to Docker SDK (port 7860)

Dockerfile

@@ -0,0 +1,28 @@
+FROM python:3.11-slim
+
+# System deps (build tools for some wheels, curl for healthcheck)
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    build-essential curl \
+    && rm -rf /var/lib/apt/lists/*
+
+# Run as non-root user (Hugging Face Spaces convention: uid 1000)
+RUN useradd -m -u 1000 user
+USER user
+ENV HOME=/home/user \
+    PATH=/home/user/.local/bin:$PATH
+
+WORKDIR $HOME/app
+
+# Install Python dependencies first (better layer caching)
+COPY --chown=user requirements.txt .
+RUN pip install --no-cache-dir --upgrade pip \
+    && pip install --no-cache-dir -r requirements.txt
+
+# Copy the rest of the app
+COPY --chown=user . .
+
+# Hugging Face Spaces expects the app on port 7860
+EXPOSE 7860
+
+CMD ["streamlit", "run", "demo.py", \
+     "--server.port=7860", "--server.address=0.0.0.0"]

README.md

@@ -3,8 +3,8 @@ title: Metadata Hierarchy Explorer
 emoji: 🌿
 colorFrom: green
 colorTo: blue
-sdk: streamlit
-app_file: demo.py
+sdk: docker
+app_port: 7860
 pinned: false
 license: mit
 ---