Add CLAUDE.md with project overview and dev commands

.github/workflows/ci.yml

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+name: CI
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+    branches: [master]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [8, 10, 12, 14, 16, 18, 20, 22]
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node-version }}
+      - run: npm install
+      - run: npm test

CLAUDE.md

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+# CLAUDE.md
+
+## Project overview
+
+recursive-readdir is a Node.js utility that recursively lists all files in a directory and its subdirectories. It supports filtering via glob patterns (minimatch) and custom functions, with both callback and Promise APIs.
+
+- **Language:** JavaScript (CommonJS, Node.js >=6.0.0)
+- **Single source file:** `index.js`
+- **Production dependency:** `minimatch`
+
+## Commands
+
+```bash
+# Install dependencies
+npm install
+
+# Run tests
+npm test
+```
+
+There is no build step, linter, or formatter configured.
+
+## Architecture
+
+- `index.js` — entire library source (~96 lines). Exports a single function `readdir(path, [ignores], [callback])`.
+- `test/recursive-readdir-test.js` — Mocha test suite with fixtures in `test/testdir/`, `test/testdirBeta/`, and `test/testsymlinks/`.
+
+## Testing
+
+Tests use Mocha with Node's built-in `assert` module. Test fixtures are checked-in directories under `test/`. Always run `npm test` to verify changes.