docs: document extending events

[tcheeric]

Summary

• document factory/registry architecture for creating and extending events
• describe how to add new event types, testing expectations, and contribution guidelines

Testing

• mvn -q verify (fails: Could not find a valid Docker environment)

---

https://chatgpt.com/codex/tasks/task_b_68a48d9f22bc8331984698e3e71fb433

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[Copilot]

Pull Request Overview

Documents the project's architecture for extending events using factories and registries, providing guidelines for contributors who want to add new event types to the Nostr implementation.

• Documents the factory/registry pattern used for event creation and tag management
• Provides step-by-step instructions for adding new event types
• Establishes testing and contribution requirements

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[Copilot]

The reference to AGENTS.md appears to be a non-standard filename for contribution guidelines. Consider verifying this filename exists or if it should be CONTRIBUTING.md which is the conventional name for contribution guidelines.

Suggested change

	Refer to the repository's `AGENTS.md` for the full list of contribution expectations.
	Refer to the repository's `CONTRIBUTING.md` for the full list of contribution expectations.