Rework simulation rules

src/ReactorMaintenance.Simulation/Models/UndergroundCell.cs

@@ -5,6 +5,7 @@ public sealed record UndergroundCell
     public EUndergroundState State { get; init; }
     public float Amount { get; init; }
     public float Intensity { get; init; }
+    public int StructuralIntegrity { get; init; } = Balancing.Current.MaxStructuralIntegrity;
 
     public bool IsPresent => State != EUndergroundState.Absent;
     public bool CarriesFlow => State is EUndergroundState.Intact or EUndergroundState.Leaking;