fix: clean up resize observer

[DarkGenius]

Summary

• ensure ResizeObserver is disconnected and debounced callback cancelled in useOverflowingHorizontalListItems

Testing

• npm test
• npm run lint:js

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https://chatgpt.com/s/cd_68ab477293d081918541317bf42bb49b

Summary by CodeRabbit

• New Features
  • No user-facing features added.
• Bug Fixes
  • Prevented rare initialization errors when the footer menu isn’t present.
  • Ensured width updates only occur when the element exists, avoiding null access.
• Refactor
  • Improved cleanup of observers and debounced handlers to reduce potential leaks and stabilize behavior.
• Tests
  • No changes.
• Documentation
  • No changes.

[gravity-ui-bot]

Preview is ready.

[gravity-ui-bot]

Playwright Test Component is ready.