Teach Claude your project — once

`CLAUDE.md` is a markdown file at your repo root that Claude reads at the start of every session. Put your project's conventions, commands, and 'don'ts' here so you stop repeating yourself.

# CLAUDE.md
## Commands
- Dev: bun dev
- Test: bun test
## Conventions
- Use TanStack Router, never react-router
## Don'ts
- Never commit directly to main

• ✓Lives at the repo root (commit it)
• ✓Never put secrets here — it's in git
• ✓Subfolders can have their own CLAUDE.md too