perf: replace badge rate limiter timestamp arrays with sliding window…

[Kokila-chandrakar]

Summary

Optimized the existing Badge Rate Limiter by replacing timestamp array-based tracking with a sliding window counter approach to improve performance and memory efficiency.

Closes #1818

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Type of Change

• Bug fix
• New feature
• Documentation update
• Refactor / code cleanup

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Changes Made

• Replaced timestamp array-based rate limiting logic with sliding window counter
• Improved memory efficiency by removing per-request timestamp storage
• Enhanced performance under high request load
• Updated and validated test cases for new logic
• Ensured backward-compatible rate limiting behavior

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How to Test

Steps for the reviewer to verify this works:

1. Run the application locally
2. Trigger badge requests repeatedly within a short time window
3. Verify rate limiting behaves correctly under load
4. Run test suite:

   npm run test

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• level:beginner — 20 pts
• level:intermediate — 35 pts
• level:advanced — 55 pts
• level:critical — 80 pts

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[Priyanshu-byte-coder]

Thanks! PR #1842 implements a more accurate true sliding window counter (using prev/curr window interpolation) for the same feature. Closing this in favor of that implementation.