Finalized Python module integration

`convert_html_to_markdown.py` is now copied, owner-changed, and is finally executed after the web scraping content is produced.

Dockerfile

@@ -55,4 +55,4 @@ COPY --chown=myuser . ./
 
 # Run the image. If you know you won't need headful browsers,
 # you can remove the XVFB start script for a micro perf gain.
-CMD ./start_xvfb_and_run_cmd.sh && npm run start:prod --silent
+CMD ./start_xvfb_and_run_cmd.sh && npm run start:prod --silent && python3 conv_html_to_markdown.py