Automated fix by @leftibot.

What changed

Fix #10: Add grammar railroad diagram to the hourly build process
Add a new GitHub Actions workflow (update-grammar.yml) that runs hourly
to fetch the EBNF grammar from ChaiScript/ChaiScript and generate
navigable railroad diagrams using the RR tool (GuntherRademacher/rr).
A new grammar.html page embeds the generated diagram with a navigation
link added to the site header. Regression tests verify the workflow
configuration, grammar page, and navigation integration.
Co-Authored-By: Claude Opus 4.6 (1M context) [email protected]

Files

 .github/workflows/update-grammar.yml | 59 ++++++++++++++++++++++++++++++++++++
 _includes/header.html                |  3 ++
 grammar.html                         | 50 ++++++++++++++++++++++++++++++
 test_playground.sh                   | 18 ++++++++++-
 4 files changed, 129 insertions(+), 1 deletion(-)

Closes #10

Triggered by @lefticus.