feat: add recipe scraping script and update Docker image

- scripts/scrape-recipe: Python script using recipe-scrapers to extract
  schema.org JSON-LD from a recipe URL (or local HTML file for testing)
- Dockerfile: add Python3 + recipe-scrapers in virtualenv, install the
  scrape-recipe script at /usr/local/bin/scrape-recipe

Dockerfile

@@ -1,15 +1,22 @@
 FROM debian:bookworm-slim
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
-    ca-certificates curl tini && \
+    ca-certificates curl python3 python3-pip python3-venv tini && \
     rm -rf /var/lib/apt/lists/*
 
+# Install recipe-scrapers in a virtualenv to isolate dependencies.
+RUN python3 -m venv /opt/roux-venv && \
+    /opt/roux-venv/bin/pip install --no-cache-dir recipe-scrapers==15.11.0 && \
+    rm -rf /root/.cache/pip
+
 # Build timestamp — read at runtime for diagnostics.
 RUN mkdir -p /build && date -u '+%Y-%m-%d %H:%M UTC' > /build/build-time
 
 ADD roux-server /usr/local/bin/roux-server
+ADD scripts/scrape-recipe /usr/local/bin/scrape-recipe
 
-RUN chmod +x /usr/local/bin/roux-server
+RUN chmod +x /usr/local/bin/roux-server /usr/local/bin/scrape-recipe
+ENV PATH="/opt/roux-venv/bin:${PATH}"
 
 ENTRYPOINT ["/usr/bin/tini", "-s", "--"]