AtAuth

Add TypeScript tests and CHANGELOG (#3) master

* Fix TypeScript VERSION constant to match package.json Closes #1 (partial) * Add TypeScript unit tests for token and validation modules Tests cover: - Token decoding, expiration, remaining time calculations - DID and handle validation - OAuth state parsing with security checks - App ID validation - HTTPS enforcement in production Closes #1 * Add CHANGELOG.md Document changes for v1.0.0 and v1.2.0 releases using Keep a Changelog format. Closes #2 * Fix unused imports in validation.test.ts ---------