docs: add CONTRIBUTING.md

CONTRIBUTING.md

@@ -0,0 +1,64 @@
+# Contributing
+
+Thanks for your interest in contributing to blockchain-wallet-validator!
+
+## Prerequisites
+
+- Node.js 18+
+- pnpm
+
+## Setup
+
+```bash
+git clone https://github.com/sergical/blockchain-wallet-validator.git
+cd blockchain-wallet-validator
+pnpm install
+```
+
+## Development
+
+```bash
+# Run tests
+pnpm test
+
+# Run tests in watch mode
+pnpm test:watch
+
+# Run tests with coverage
+pnpm test:coverage
+
+# Lint
+pnpm lint
+
+# Format
+pnpm format
+
+# Build
+pnpm build
+
+# Check bundle size
+pnpm size
+```
+
+## Adding a New Network
+
+1. Add the regex pattern to the `patterns` object in `src/index.ts`
+2. Add validation logic in `validateWalletAddress()` (order matters for conflict resolution)
+3. Add tests covering:
+   - Valid mainnet addresses
+   - Valid testnet addresses (if applicable)
+   - Invalid formats and edge cases
+4. Run `pnpm size` to ensure bundle size stays within limits
+
+## Submitting a PR
+
+1. Fork the repo and create a branch from `main`
+2. Make your changes
+3. Ensure tests pass: `pnpm test`
+4. Ensure coverage thresholds are met: `pnpm test:coverage`
+5. Ensure bundle size is within limits: `pnpm size`
+6. Submit a PR with a clear description of the changes
+
+## Code Style
+
+This project uses ESLint and Prettier. Run `pnpm format` before committing.