Add "click outside to close" functionality to file tree browser

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Summary

This is a follow-up to #541102 (closed) to enhance the file tree browser (FTB) user experience by implementing "click outside to close" functionality, similar to how the super sidebar behaves.

Proposal

Implement "click outside to close" functionality for the file tree browser that matches the super sidebar behavior:

• When the file tree browser is open as a modal/panel (on md and lg viewports), clicking outside the browser should close it
• This should work consistently with the existing toggle button functionality
• The behavior should match the super sidebar's implementation for consistency

Context

See !204775 (comment 2759848874)