Add SPEC, PLAN, Dockerfile, compose, env example, app modules, CI workflow

Dockerfile

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+FROM python:3.12-slim
+
+RUN useradd --create-home --shell /bin/bash appuser
+
+WORKDIR /app
+
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+COPY app/ ./app/
+
+RUN mkdir -p /data && chown -R appuser:appuser /app /data
+
+USER appuser
+
+ENV PYTHONUNBUFFERED=1
+
+EXPOSE 8090
+
+CMD ["python", "-m", "app.main"]