refactor: upgrade react-transition-group v2 to v4 and migrate string refs to createRef

[ankita10119]

Changes

Upgrades react-transition-group from ^2.2.1 to ^4.4.5. RTG v4 removes internal use of the deprecated ReactDOM.findDOMNode, requiring an explicit nodeRef prop on CSSTransition. This in turn drove a full migration from legacy string refs (this.refs.*) and ReactDOM.findDOMNode calls to React.createRef() across the UI layer.

Components changed:

• ui/box/chrome.jsx - CSSTransition gains nodeRef props; screen, auxiliary, and globalMessage refs converted to createRef
• ui/box/container.jsx - this.refs.chrome → this.chromeRef
• ui/box/header.jsx - getDOMNode uses this.headerRef.current instead of findDOMNode(this)
• ui/box/multisize_slide.js - this.refs[key] replaced with a childRefs map of createRef instances
• ui/list.jsx - this.refs.highlighted and findDOMNode removed
• All 8 input components (captcha, email, mfa_code, password, phone_number, text, username, vcode) - this.refs.input → this.inputRef.current

Also removes the unused events dev dependency.

References

• Backport of changes from fix: resolve null domain handling and v13 lock bug fixes #2807

Testing

• This change adds unit test coverage
• This change adds integration test coverage
• This change has been tested on the latest version of the platform/language

All 401 existing tests pass. Visual/animation behaviour should be verified manually, particularly the slide transition between screens and the auxiliary pane animation.

Checklist

• I have read the Auth0 general contribution guidelines
• I have read the Auth0 Code of Conduct
• All code quality tools/guidelines have been run/followed
• All relevant assets have been compiled