Write the rules file for my project

I'm building <one sentence> with <stack>, deployed to <host>. Here's the
project as it stands: <paste the file list and one representative file>

Write a short conventions file for AI tools to read at the start of every
session, such as CLAUDE.md. Include:
- How to run it locally and how to deploy it to this host.
- The stack's conventions this project actually follows, taken from the
  code rather than from general advice.
- What's deliberately unusual here, and why.
- What must never happen: files not to edit, commands not to run.

Under 60 lines. Only things that can't be worked out from the code.