docs: update leaderboard screenshot with fully populated matrix rain

[Yashaswini-K-P]

Description

Updated the leaderboard screenshot in the README to show the Matrix rain animation fully populated across the entire page, resolving the previous issue where the lower half appeared empty.

Linked Issue

Fixes #348

Changes Made

• Replaced the previous README leaderboard screenshot with an updated version captured with a fully populated Matrix rain background animation.

Type of Change

• Documentation update

Testing

• Tested locally
• No console errors introduced

Checklist

• My code follows the project's coding style
• I have formatted my code locally by running npx prettier --write . before submitting
• I am submitting my PR from a dedicated feature/* branch, not the main branch
• I have performed a self-review of my code
• My changes generate no new warnings or errors
• I have updated documentation if required
• I have linked the relevant issue

Screenshots / Screen Recording

• Included in the README update.

[github-actions]

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