audit work, fixed StellaOps.sln warnings/errors, fixed tests, sprints work, new advisories

src/Policy/__Libraries/StellaOps.Policy/Gates/BudgetThresholdNotifier.cs

@@ -6,6 +6,7 @@
 // -----------------------------------------------------------------------------
 
 using System.Collections.Immutable;
+using System.Globalization;
 using System.Text.Json.Nodes;
 using Microsoft.Extensions.Logging;
 
@@ -147,7 +148,7 @@ public sealed class BudgetThresholdNotifier
             ["percentageUsed"] = budget.PercentageUsed,
             ["status"] = budget.Status.ToString().ToLowerInvariant(),
             ["severity"] = severity,
-            ["timestamp"] = timeProvider.GetUtcNow().ToString("O")
+            ["timestamp"] = timeProvider.GetUtcNow().ToString("O", CultureInfo.InvariantCulture)
         };
     }
 }