feat: add .npmignore, CHANGELOG.md, and SECURITY.md; update package.json with metadata and keywords

Author: marcvelmer

.npmignore

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+# Source files
+src/
+test/
+tests/
+
+# Development files
+.env
+.env.*
+*.env
+.envrc
+
+# Build and development tools
+rollup.config.js
+jest.config.js
+tsconfig.json
+.eslintrc.json
+.prettierrc.json
+.lintstagedrc.json
+
+# Documentation source
+docs/
+*.md
+!README.md
+!LICENSE
+
+# Examples and demos
+examples/
+
+# Git and CI
+.git/
+.github/
+.gitignore
+.gitattributes
+
+# IDE and editor files
+.idea/
+.vscode/
+*.swp
+*.swo
+*~
+
+# OS generated files
+.DS_Store
+.DS_Store?
+._*
+.Spotlight-V100
+.Trashes
+ehthumbs.db
+Thumbs.db
+
+# Dependencies
+node_modules/
+
+# Logs
+logs/
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+lerna-debug.log*
+
+# Coverage and test results
+coverage/
+.nyc_output/
+junit.xml
+
+# Temporary files
+tmp/
+temp/
+.tmp/
+
+# Package managers
+yarn.lock
+package-lock.json
+pnpm-lock.yaml
+
+# Development scripts
+scripts/
+tools/
+
+# Backup files
+*.bak
+*.backup
+*.old
+
+# Local configuration
+.env.local
+.env.development.local
+.env.test.local
+.env.production.local

CHANGELOG.md

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+# Changelog
+
+All notable changes to the Vocdoni DaVinci SDK will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+### Added
+- Initial public release preparation
+- Complete TypeScript SDK for Vocdoni DaVinci protocol
+- Support for both MerkleTree and CSP census types
+- Comprehensive examples (script and UI)
+- Full test coverage with unit and integration tests
+
+## [0.0.1] - 2024-12-01
+
+### Added
+- **Core SDK Features**
+  - Complete DaVinci SDK implementation with TypeScript support
+  - Process creation and management capabilities
+  - Vote submission with homomorphic encryption
+  - Census creation and management (MerkleTree and CSP)
+  - Smart contract integration for Ethereum networks
+  - Support for Sepolia testnet and Ethereum mainnet
+
+- **API Services**
+  - Sequencer API client for vote processing
+  - Census API client for participant management
+  - Base API service with error handling and retries
+  - Comprehensive type definitions
+
+- **Cryptographic Features**
+  - Homomorphic encryption for vote privacy
+  - zk-SNARK proof generation and verification
+  - Circom circuit integration
+  - CSP (Census Service Provider) signature support
+
+- **Developer Experience**
+  - Complete TypeScript definitions
+  - ESM and CommonJS module support
+  - Browser and Node.js compatibility
+  - Comprehensive JSDoc documentation
+  - Multiple bundle formats (UMD, ES modules, CommonJS)
+
+- **Examples and Documentation**
+  - Script example with complete voting workflow
+  - React UI example with wallet integration
+  - Comprehensive README with usage examples
+  - API reference documentation
+  - Contributing guidelines
+
+- **Testing Infrastructure**
+  - Unit tests for all core functionality
+  - Integration tests with real network interactions
+  - Jest test framework setup
+  - Test utilities and helpers
+
+- **Build and Development**
+  - Rollup build configuration for multiple formats
+  - TypeScript compilation with strict mode
+  - ESLint and Prettier configuration
+  - Automated formatting and linting
+  - Git hooks for code quality
+
+- **Quality Assurance**
+  - Comprehensive error handling
+  - Input validation and sanitization
+  - Network timeout and retry logic
+  - Memory-efficient proof generation
+
+### Technical Details
+- **Dependencies**
+  - ethers.js v6 for Ethereum interactions
+  - axios for HTTP requests
+  - snarkjs for zk-SNARK operations
+  - @vocdoni/davinci-contracts for smart contract ABIs
+
+- **Supported Networks**
+  - Ethereum Sepolia testnet
+  - Ethereum mainnet
+  - Custom network configuration support
+
+- **Supported Environments**
+  - Node.js 16+
+  - Modern browsers (Chrome, Firefox, Safari, Edge)
+  - React applications
+  - Vue.js applications
+  - Vanilla JavaScript/TypeScript projects
+
+### Known Issues
+- None at initial release
+
+---
+
+## Release Notes
+
+### Version 0.0.1 - Initial Release
+
+This is the first public release of the Vocdoni DaVinci SDK, providing a complete TypeScript interface for building decentralized voting applications on the Vocdoni DaVinci protocol.
+
+**Key Features:**
+- 🔒 **Privacy-First**: Homomorphic encryption ensures vote privacy
+- 🛡️ **Secure**: Built on battle-tested cryptographic primitives  
+- ⚡ **Easy Integration**: Simple, intuitive API for developers
+- 🌐 **Decentralized**: No central authority controls the voting process
+- 📱 **Cross-Platform**: Works in browsers, Node.js, and mobile apps
+- 🔧 **TypeScript**: Full type safety and excellent developer experience
+
+**Getting Started:**
+```bash
+npm install @vocdoni/davinci-sdk ethers
+```
+
+See the [README](README.md) for complete usage examples and API documentation.
+
+**Breaking Changes:** N/A (initial release)
+
+**Migration Guide:** N/A (initial release)
+
+---
+
+## Contributing
+
+When contributing to this project, please:
+
+1. Follow the [Contributing Guidelines](CONTRIBUTING.md)
+2. Update this CHANGELOG with your changes
+3. Use the format described in [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
+4. Group changes by type: Added, Changed, Deprecated, Removed, Fixed, Security
+
+## Links
+
+- [GitHub Repository](https://github.com/vocdoni/davinci-sdk)
+- [npm Package](https://www.npmjs.com/package/@vocdoni/davinci-sdk)
+- [Documentation](https://docs.vocdoni.io)
+- [Issue Tracker](https://github.com/vocdoni/davinci-sdk/issues)