🧪 [Testing] Add test for year-by-year impact log toggle

[singhaditya21]

🎯 What: The testing gap for the 'year-card' expand/collapse toggle logic in script.js has been addressed.
📊 Coverage: The test covers that the first card expands by default, the toggle opens and closes panels appropriately on click, and rogue cards without headers don't break the functionality.
✨ Result: Improved test coverage by verifying the core interaction of the impact log using a python Playwright DOM mock test.

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PR created automatically by Jules for task 5324044347868779803 started by @singhaditya21

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