feat: add headless Chromium fallback to recipe scraper

Uses Playwright to drive Chromium when the primary requests-based
fetch fails (e.g., Cloudflare, JS-required pages). Hybrid approach:
try fast path first, fall back to Chromium only on failure.

Dockerfile: add playwright==1.52.0 pip package, run playwright
install-deps chromium + playwright install chromium to download
the browser and all system libraries.

scrape-recipe: add fetch_with_chromium() that tries Playwright
first, then chromium --headless --dump-dom as a subprocess fallback.
Modify main() to catch primary fetch errors and call Chromium
fallback before giving up.

Dockerfile

@@ -4,11 +4,15 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates curl python3 python3-pip python3-venv tini && \
     rm -rf /var/lib/apt/lists/*
 
-# Install recipe-scrapers in a virtualenv to isolate dependencies.
+# Install recipe-scrapers and Playwright 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 && \
+    /opt/roux-venv/bin/pip install --no-cache-dir recipe-scrapers==15.11.0 playwright==1.52.0 && \
     rm -rf /root/.cache/pip
 
+# Install Playwright system dependencies and Chromium browser.
+RUN /opt/roux-venv/bin/playwright install-deps chromium && \
+    /opt/roux-venv/bin/playwright install chromium
+
 # Build timestamp — read at runtime for diagnostics.
 RUN mkdir -p /build && date -u '+%Y-%m-%d %H:%M UTC' > /build/build-time