feat(types): Add strict TypeScript definitions & improve CommonJS compatibility

[Allen-Bayern]

This PR enhances TypeScript support with the following improvements:

🔧 Core Changes

1. Added complete TypeScript type definitions (index.d.ts) with:

• Strict event type constraints via generics
• Proper CommonJS export declarations (export =)
• Declaration merging for TinyEmitter static property

2. Fixed module export alignment with original implementation:

// Now supports both usage patterns:
const Emitter = require('tiny-emitter');
new Emitter(); 

import { TinyEmitter } from 'tiny-emitter';
new TinyEmitter();

3. Added comprehensive TypeScript documentation in README
4. Verified type safety with TS 4.9+ strict mode

✅ Validation

• Added type tests in test/types.test.ts
• Verified working with:

npm version patch && npm publish

📦 Release Request

Would you please consider:

1. Merging this PR
2. Publishing a new minor/patch version to NPM

npm version patch && npm publish

This will significantly improve the experience for TypeScript users while maintaining full backward compatibility.