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

AGENTS.md

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+This file provides guidance to AI coding agents when working with code in this repository.
+
+## What this project is
+
+A Visual Studio Code extension for [code_ownership](https://github.com/rubyatscale/code_ownership). It shows the owning team for the currently open file and lets developers quickly navigate to ownership configuration.
+
+## Commands
+
+```bash
+npm install
+
+# Build (webpack)
+npm run build
+
+# Production build
+npm run build:prod
+
+# Watch mode
+npm run watch
+
+# Run tests
+npm test
+
+# Lint
+npm run lint
+
+# Auto-fix lint
+npm run fix
+```
+
+## Architecture
+
+- `src/` — TypeScript source; the extension queries the `code_ownership` Ruby gem (or a language server) to resolve ownership for the active file and displays it in the status bar
+- `package.json` — VS Code extension manifest, activation events, contributed commands, and webpack build config
+- `webpack.config.js` — bundles the extension for distribution

CLAUDE.md

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+@AGENTS.md