Add AGENTS.md and CLAUDE.md for AI coding agent guidance

Author: dduugg

AGENTS.md

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+# AGENTS.md
+
+This file provides guidance to AI coding agents when working with code in this repository.
+
+## What this project is
+
+`query_packwerk` is a Ruby gem for querying and analyzing [packwerk](https://github.com/Shopify/packwerk) violations and dependencies. It provides a fluent API and an interactive console for exploring `package.yml` and `package_todo.yml` files.
+
+## Commands
+
+```bash
+bundle install
+
+# Run all tests (RSpec)
+bundle exec rspec
+
+# Run a single spec file
+bundle exec rspec spec/path/to/spec.rb
+
+# Lint
+bundle exec rubocop
+bundle exec rubocop -a  # auto-correct
+
+# Type checking (Sorbet)
+bundle exec srb tc
+```
+
+## Architecture
+
+- `lib/query_packwerk.rb` — entry point and public API
+- `lib/query_packwerk/` — query classes for violations, packages, and dependency graphs; also includes an interactive console (REPL) interface
+- `spec/` — RSpec tests; `spec/fixtures/` holds sample packwerk app structures

CLAUDE.md

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+@AGENTS.md