docs: Add comprehensive CLAUDE.md documentation

[natthasath]

• Created detailed project documentation for Claude Code
• Includes project overview, technology stack, and architecture
• Documents development workflow and common tasks
• Provides quick reference for developers
• Removed CLAUDE.md from .gitignore to track this documentation

This file helps Claude Code and developers understand the Hi.Events project structure, codebase organization, and development practices.

Thank you for creating a PR! We appreciate your contribution to Hi.Events.

To make the process as smooth as possible, please ensure you've read the contributing guidelines before proceeding.

Please include a summary of the changes and the issue being fixed or the feature being added. The more detail, the better!

Checklist

• I have read the contributing guidelines.
• My code is of good quality and follows the coding standards of the project.
• I have tested my changes, and they work as expected.

Thank you for your contribution! 🎉

[github-actions]

Thank you for your submission, we really appreciate it. Like many open-source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution. You can sign the CLA by just posting a Pull Request Comment same as the below format.

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I have read the CLA Document and I hereby sign the CLA

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_{You can retrigger this bot by commenting recheck in this Pull Request. Posted by the CLA Assistant Lite bot.}