⚡ Bolt: Optimize BuildCandidateRoutes LINQ allocation overhead

[google-labs-jules]

💡 What: Materialized activeProducers and activeConsumers lists outside of the nested foreach loops in the BuildCandidateRoutes methods of TemporalNetworkSimulationEngine.cs and MixedRouting.cs.

🎯 Why: The original implementation was re-evaluating the LINQ queries (.Where(...), .Select(...)) on context.Demand and context.Supply for every single iteration of the outer producer loops. This caused severe O(P * C) redundant enumerator allocations and CPU evaluations during intensive capacity bidding phases, significantly slowing down large simulations.

📊 Impact: Reduces redundant LINQ enumerations and object allocations from O(P * C) to O(P + C) for every call to BuildCandidateRoutes. This dramatically improves throughput during global routing capacity bidding (which runs repeatedly in a while (true) loop).

🔬 Measurement: The performance improvement can be measured by running any simulation benchmark involving complex networks with many producing and consuming nodes. Run the application, load a complex model with mixed routing, and observe reduced CPU utilization and garbage collection pauses during the routing passes. The test suite ran cleanly (129/129 passed).

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PR created automatically by Jules for task 17572096243513606914 started by @wnj00524

[google-labs-jules]

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