Add click outside handler to close time travel dropdown

[coderabbitai[bot]]

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Context

The time travel dropdown in the project map should close when clicking outside of it to improve user experience.

Implementation Details

• Add click outside handler using useEffect and useRef hooks
• Close the dropdown when clicking outside of the dropdown container
• Clean up event listener on component unmount

References

• PR: #2329
• Comment: https://github.com/Plant-for-the-Planet-org/planet-webapp/pull/2329#discussion_r1924925010