Project rules file (AGENTS.md / CLAUDE.md / Cursor rules)

Create a project rules file for this repo. Inspect package.json, the folder structure, and config files first, then write it in this structure:

# Project overview
- What the app does (2 lines), stack and versions actually in package.json.
# Commands
- install, dev, build, test, lint — exact commands.
# Conventions
- Folder layout, naming, styling approach, state management, data fetching pattern.
# Rules for the AI
- Make the smallest change that solves the task. Don't refactor unrelated code.
- Never put secrets in client code; server-only env vars have no public prefix.
- Run the build and tests before saying a task is done.
- Ask before adding a new dependency.
- When an error repeats twice, stop and diagnose instead of patching again.
# Known gotchas
- [leave placeholders for me to fill]

Keep it under 80 lines. Save it as AGENTS.md (I'll copy it to CLAUDE.md or a Cursor rule if my tool needs that name).