⚡ Bolt: [performance improvement] Precompute lowercase operations to prevent N*M complexity bottleneck

[raccioly]

💡 What
Precomputed lowercase tracking content and hoisted TODO search string .toLowerCase() extractions outside the N*M .some() closure in cli/validators/todo-tracking.mjs.

🎯 Why
When comparing extracted todos to loaded tracking documentation, the .toLowerCase() and text subsetting operations were repeatedly recalculating exactly the same outputs inside an inner nested closure, introducing an unnecessary N*M processing bottleneck during validations.

📊 Impact
Prevents garbage collector overload and excessive CPU cycles by running string transformations O(M) and O(N) times respectively during file tracking validations rather than O(N*M) times.

🔬 Measurement
Tests were successfully executed using Node.js's native test runner (pnpm test equivalent) to confirm logic equivalency. Both docguard guard and general CLI commands remain unaffected while operating without the structural regression overhead.

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PR created automatically by Jules for task 13119780152435250170 started by @raccioly

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