⚡ Bolt: [O(1) label deduplication]

[coredipper]

💡 What: Replace list-based deduplication (if item not in seen: seen.append(item)) with dict.fromkeys for footnote labels.
🎯 Why: Searching a list for membership is an $O(N)$ operation, causing the marker extraction process to be $O(N^2)$ based on the number of markers in the text.
📊 Impact: Changes deduplication from $O(N^2)$ to $O(N)$ for parsing footnotes in page bodies, improving parse speed for large files.
🔬 Measurement: Observe lower cpu usage during marker deduplication in files with heavily footnoted bodies.

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PR created automatically by Jules for task 16863514154974805901 started by @coredipper

[google-labs-jules]

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