⚡ Bolt: List rendering & filtering performance optimization

[MrAlokTech]

💡 What:
Implemented a data loading optimization by introducing a prepareSearchIndex function that pre-calculates expensive derived properties (_searchStr, _isNew, _formattedDate) for all PDF objects upon initialization, rather than calculating them inline during every UI render cycle.

🎯 Why:
The application suffered from UI thread blocking and jank when typing in the search bar or changing filters. This occurred because functions like new Date(), toLocaleDateString(), .toLowerCase(), and string concatenations were being repeatedly and redundantly executed synchronously for every item inside the high-frequency renderPDFs and createPDFCard rendering loops.

📊 Impact:

• Reduces Date object instantiations to O(N) during data load instead of O(N * R) where R is the number of re-renders.
• Reduces .toLowerCase() string operations in the search filter loop from 4 calls per item to 0 (replaced with a single includes() lookup against the pre-calculated _searchStr).
• Significantly improves responsiveness of the search input field and category filter buttons.

🔬 Measurement:
Run the Playwright UI verification tests, or manually start the server and observe the responsiveness of the UI when typing into the search input. It will be noticeably faster on large datasets. Critical learnings have been documented in .jules/bolt.md.

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PR created automatically by Jules for task 8689871990632569729 started by @MrAlokTech

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