⚡ Bolt: Optimize ViewModel array allocations

[acebytes]

• 💡 What: Replaced eager .filter { ... }.isEmpty with .contains(where:) in hasSelection, and added .lazy to selectedSize reduction.
• 🎯 Why: hasSelection is bound to view modifiers like .disabled(), causing O(N) array allocations on every SwiftUI render frame. selectedSize also generated temporary array copies during its sum reduction.
• 📊 Impact: Reduces memory churn to zero and changes the check from O(N) eager to an O(1) best-case short-circuiting evaluation.
• 🔬 Measurement: The UI thread will experience less overhead and garbage collection pauses when frequently re-rendering the view.

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PR created automatically by Jules for task 16789025288954866978 started by @acebytes

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