Improve custom event handling and dispatching

[coderabbitai]

Based on CodeRabbit review in PR #11: #11

Event Handling Improvements:

1. Fix Event Dispatching Logic (src/allonsh.js:506-515)

• Currently dispatches both dragenter and dragleave on drop
• This is semantically confusing
• Suggestion: Only dispatch allonsh-drop on drop completion
• Future: Track hover states during drag for proper enter/leave events

2. Event Consistency

• Ensure events are dispatched at appropriate times
• Document expected event sequence in docs

Files to Update:

• src/allonsh.js
• docs/allonsh.md

Priority: Low

Improves API consistency and developer experience with events.