⚡ Bolt: [performance improvement] Optimize computeBlockSummaryStats

[Howchie]

💡 What: Optimized the computeBlockSummaryStats function in packages/core/src/runtime/blockSummary.ts. Replaced Array.prototype.filter and subsequent loop with a single for loop to eliminate intermediate array allocations. Also hoisted the call to Object.entries(where) outside the loop so it's only executed once per function call, instead of once per trial result.

🎯 Why: The previous implementation performed multiple O(N) array allocations and executed expensive Object/Array methods (Object.entries, Array.isArray, Array.prototype.some) on every single iteration inside the filter callback, causing unnecessary CPU and memory overhead when analyzing large trial result arrays.

📊 Impact: Achieves a ~4.5x improvement in execution speed (from ~1.89ms down to ~0.4ms for 10,000 trials in local benchmarks) and significantly reduces memory allocation overhead.

🔬 Measurement: The performance improvement was measured using a custom tinybench script simulating 10,000 trial results with a where condition, comparing the execution time of the original implementation versus the single-pass implementation. The logic has also been verified against existing unit tests in @experiments/core.

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PR created automatically by Jules for task 12757949840353908432 started by @Howchie

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