⚡ Bolt: Optimize selection mutations to batch UI updates

[acebytes]

💡 What
Replaced individual for loop mutations of the @Published arrays scanResults and nodeModulesItems with batched .map assignments in CacheoutViewModel.swift. Added comments to explain the performance optimization. Also created .jules/bolt.md documenting this finding.

🎯 Why
In SwiftUI, when a @Published property holds an array of value types (like structs), mutating any element of that array triggers the property's willSet observer. Doing this inside a loop triggers a separate UI update notification (objectWillChange) for every single iteration, causing massive unnecessary CPU overhead and UI re-evaluation.

📊 Impact
Reduces UI update notifications during bulk selection actions ("Select All", "Deselect All", etc.) from O(N) to exactly 1, vastly improving responsiveness when handling hundreds or thousands of cached items or node_modules folders.

🔬 Measurement
Verify by triggering a bulk action (e.g. "Select All") on a scan with a large number of results; the UI freeze and CPU spike previously associated with the O(N) updates should be eliminated.

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PR created automatically by Jules for task 715615417954354689 started by @acebytes

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