Initial release of uptimecheck: simple, dependency-free uptime monitoring for URLs and APIs.

- Check if one or multiple URLs/endpoints are up, with response time and HTTP status.
- Supports batch checking from files, with comment lines.
- History and trend tracking: save results as JSON lines for later review.
- View history with filters (by URL, recent N entries).
- Configurable HTTP timeout.
- Intuitive output with clear ✅/❌ indicators, response times, and summary.
- Exit codes for easy integration with CI or scripts.