feat(scaffold): add Dockerfile [skip ci]

Dockerfile

@@ -0,0 +1,25 @@
+# ---- Build stage (install deps) ----
+FROM python:3.12-slim AS build
+WORKDIR /app
+
+RUN pip install --upgrade pip
+COPY requirements.txt .
+RUN pip install --no-cache-dir --prefix=/install -r requirements.txt
+
+# ---- Runtime stage ----
+FROM python:3.12-slim
+WORKDIR /app
+
+# Non-root user
+RUN addgroup --system appgroup && adduser --system --ingroup appgroup appuser
+USER appuser
+
+COPY --from=build /install /usr/local
+COPY app/ ./app/
+
+EXPOSE 8000
+
+HEALTHCHECK --interval=30s --timeout=5s --start-period=20s --retries=3 \
+    CMD python -c "import urllib.request; urllib.request.urlopen('http://localhost:8000/health')" || exit 1
+
+CMD ["opentelemetry-instrument", "uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000"]