docs: add CONTRIBUTING.md and CI status badge to README

CONTRIBUTING.md

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+# Contributing to agent-browser
+
+Thanks for your interest in contributing! This guide covers everything you need to get started.
+
+## Development Setup
+
+### Prerequisites
+
+- [Node.js](https://nodejs.org/) v20 or v22
+- [pnpm](https://pnpm.io/) v9+
+- [Rust](https://rustup.rs/) (optional, only needed for native binary builds)
+
+### Getting Started
+
+1. **Fork and clone the repo:**
+
+   ```bash
+   git clone https://github.com/<your-username>/agent-browser.git
+   cd agent-browser
+   ```
+
+2. **Install dependencies:**
+
+   ```bash
+   pnpm install
+   ```
+
+3. **Build the project:**
+
+   ```bash
+   pnpm build
+   ```
+
+4. **Link for local development:**
+
+   ```bash
+   pnpm link --global
+   agent-browser install  # Download Chromium
+   ```
+
+5. **Run the type checker:**
+
+   ```bash
+   pnpm typecheck
+   ```
+
+6. **Run tests:**
+
+   ```bash
+   pnpm test
+   ```
+
+### Rust Native Binary (optional)
+
+If you want to build the native Rust CLI:
+
+```bash
+pnpm build:native
+```
+
+## Coding Style
+
+- **TypeScript:** Code is written in TypeScript with strict typing enabled. Run `pnpm typecheck` to verify.
+- **Formatting:** We use Prettier. Run `pnpm format:check` before committing.
+  - Auto-fix with: `pnpm format`
+- **Linting:** Follow existing patterns in the codebase. Keep functions small and focused.
+- **Naming:** Use `camelCase` for variables/functions, `PascalCase` for types/interfaces, `kebab-case` for file names.
+- **Exports:** Prefer named exports over default exports.
+
+## How to Submit a PR
+
+1. **Create a branch** from `main`:
+
+   ```bash
+   git checkout -b your-branch-name
+   ```
+
+2. **Make your changes.** Keep commits focused and messages clear.
+
+3. **Run checks locally** before pushing:
+
+   ```bash
+   pnpm typecheck
+   pnpm format:check
+   pnpm test
+   ```
+
+4. **Push and open a PR** against `main` on GitHub.
+
+5. **In your PR description:**
+   - Describe what the change does and why
+   - Reference any related issues (e.g., `Fixes #1`)
+   - Include screenshots/terminal output if relevant
+
+6. **CI must pass.** The CI workflow runs type checks, formatting, and tests on Node 20 and 22.
+
+### PR Guidelines
+
+- Keep PRs small and focused on a single change
+- Update `CHANGELOG.md` if the change is user-facing
+- Add tests for new functionality when possible
+- Make sure `pnpm format` has been run (no trailing whitespace, consistent style)
+
+## Reporting Issues
+
+- Use [GitHub Issues](https://github.com/dextonai/agent-browser/issues) to report bugs
+- Include your OS, Node.js version, and agent-browser version
+- Provide steps to reproduce the issue
+
+## License
+
+By contributing, you agree that your contributions will be licensed under the [Apache-2.0 License](LICENSE).

README.md

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 # agent-browser
 
+[![CI](https://github.com/dextonai/agent-browser/actions/workflows/ci.yml/badge.svg)](https://github.com/dextonai/agent-browser/actions/workflows/ci.yml)
+
+> **Want to contribute?** See [CONTRIBUTING.md](CONTRIBUTING.md) for setup instructions and guidelines.
+
 Headless browser automation CLI for AI agents. Fast Rust CLI with Node.js fallback.
 
 ## Installation