sync: backend from GitHub Actions

Dockerfile

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+# GeoAI Backend — HuggingFace Docker Space
+# Python 3.11 slim
+
+FROM python:3.11-slim
+
+# HuggingFace Spaces requires port 7860
+ENV PORT=7860
+ENV PYTHONDONTWRITEBYTECODE=1
+ENV PYTHONUNBUFFERED=1
+
+WORKDIR /app
+
+# Install dependencies first (layer caching)
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+# Copy all backend source files
+COPY . .
+
+EXPOSE 7860
+
+CMD ["gunicorn", "app:app", "--bind", "0.0.0.0:7860", "--workers", "1", "--threads", "2", "--timeout", "120"]