⚡ Bolt: [performance improvement] O(1) memory allocation in Jaccard Similarity clustering loop

[garridolecca]

💡 What: Optimized jaccardSimilarity in src/utils/analysis-constants.ts to iterate over sets directly and calculate the union mathematically, completely removing the intermediate array spreads and Set allocations.
🎯 Why: jaccardSimilarity is called heavily within the clusterNewsCore inner loop, which is an O(N²) operation. The previous implementation (new Set([...a].filter(x => b.has(x)))) created thousands of temporary arrays and sets every cycle, causing severe GC pressure and blocking the main thread.
📊 Impact: Reduces memory allocation to O(1) inside a critical path, significantly lowering the frequency and duration of garbage collection pauses. It prevents main thread blocking during large analysis batches.
🔬 Measurement: Verified the function operates in O(1) memory space. Ran full test:data suite, ensuring core analysis clustering and related signal logic tests continue to pass identically. Included an entry in the performance journal (.jules/bolt.md) documenting the pattern.

Note: Did not migrate to ArcGIS JS API per boundaries "Never Make architectural changes". Code maintains exactly the same functionality with the identical function signature.

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PR created automatically by Jules for task 744591581506703694 started by @garridolecca

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