[MbappeWU]

Closes #219.

🤖 AI tooling was used for this PR: the file was drafted with an AI coding assistant, then I checked every statement against the repo and ran the commands it tells agents to run. The commit subject carries the 🤖 marker per DEVELOPMENT.md.

What

A single AGENTS.md at the repo root, as discussed in the issue. It is the short loop for an agent changing the code and points to DEVELOPMENT.md for contributor rules and publishing instead of copying them. It covers:

• What each module in pyee/ defines and which optional libraries it imports.
• The just recipes for install, format, check (Pyright), mypy, test, and lint, and what each one runs.
• Which test file covers which emitter, and that the Trio and Twisted tests import those libraries directly (they come from the dev group).
• Conventions seen in the code: the prose-style docstrings that mkdocstrings renders, Self = Any on emitter methods, Black/isort/flake8 settings, the changelog heading format, the 🤖 rule, and CONTRIBUTORS.md.
• A "Do not" section: no publishing, tagging, or releases, and no lockfile or requirements edits unless the change needs a dependency change.

Two things I noticed while checking, which the file mentions rather than fixes:

• The recipe list pasted in DEVELOPMENT.md names upload and upgrade, which the justfile does not have, and omits mypy and console, which it does. AGENTS.md tells agents to trust the justfile.
• tox.ini still lists py38-py310 while requires-python is >=3.12, so AGENTS.md points agents at just test instead of just tox.

Happy to fix either of those in a separate PR if you want.

Verification

Ran on this branch (Python 3.12, uv):

• just format: no changes
• just check: 0 errors, 0 warnings, 0 informations
• just mypy: Success: no issues found in 16 source files
• just lint: flake8 clean, Valid file: ./pyproject.toml
• just test: 52 passed

No changelog entry, since the Publishing section has the maintainer write the changelog at release time. I'm already listed in CONTRIBUTORS.md.