fix: fireEvent.mouseEnter not forwarding relatedTarget properly

[swarnim02]

Fixes #1422

Problem

fireEvent.mouseEnter was not forwarding relatedTarget properly - it would be window instead of the specified element.

Solution

Changed spread operator to explicit parameters in fire-event.js:

• (...args) => → (node, init) =>

This ensures relatedTarget and other event properties are properly passed through.

Changes

• Fixed mouseEnter, mouseLeave, pointerEnter, pointerLeave, blur, focus
• Added comprehensive tests

Testing

fireEvent.mouseEnter(element, { relatedTarget: mockElement })
// Now correctly receives mockElement instead of window