feat: add AGENTS.md for AI rules (#236)

Co-authored-by: Michael Berger <m.gonser@icloud.com>

Author: rainerhahnekamp

agents.md

@@ -0,0 +1,27 @@
+YOU MUST FOLLOW the instructions in this document
+
+# General guidelines
+- Before starting a Task do a thorough planning and break down the task in small sub-tasks 
+- Use conventional commits. The allowed scopes and types are listed in `./CONTRIBUTING.md#scope` and `./CONTRIBUTING.md#type`
+- Write atomic commits
+- Before finishing a task make sure that `yarn lint:all`, `yarn test` and `yarn build:all` pass as well as the integration tests when running `run-integration-tests.sh`. To run a single test file use `yarn vitest run -t "<test name>"`
+- Sheriff follows a zero-dependencies policy which means that adding a third-party package should be avoided at all costs.
+
+# Project Overview
+Sheriff is a TypeScript tool which enforces module boundaries and dependency rules. For more information you can read the documentation in `./docs`.
+
+## Important Packages
+- `packages/core`: This is the most important package where all the logic as well as the CLI tool lives
+- `packages/eslint-plugin`: ESLint Plugin using the core packages
+- `test-projects`: Test projects with different setups to make sure that Sheriff works as expected. Some of the setups are covered automatically with integration tests (`integration-test.sh`)
+
+# Implementing new features
+- Actual Implementation
+- Check if documentation needs to be updated/added
+- JSDoc for public members
+- Unit Tests (100%)
+- Integration Tests
+
+# Bug Fixes
+
+First reproduce the bug via a unit test. Once that is done, fix it in the code itself.