fix: Firefox textarea scrolling issues due to incorrect height calculation

[toshikwa]

Description of Changes

This pull request addresses an issue with height calculation in Firefox.

• https://bugzilla.mozilla.org/show_bug.cgi?id=1795904
• https://bugzilla.mozilla.org/show_bug.cgi?id=1787062

Changes:

• Added a Firefox-specific workaround to force layout recalculation before measuring scroll height
• Improved keyboard event handling by using React's built-in onKeyDown property
• Replaced useEffect with useLayoutEffect for better synchronization with the rendering cycle

Checklist

• Modified relevant documentation
• Verified operation in local environment
• Executed npm run cdk:test and if there are snapshot differences, execute npm run cdk:test:update-snapshot to update snapshots

Related Issues

Please list related issues as much as possible.