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

src/Cli/StellaOps.Cli/Commands/CommandHandlers.Drift.cs

@@ -5,6 +5,7 @@
 // Description: Command handlers for reachability drift CLI.
 // -----------------------------------------------------------------------------
 
+using System.Globalization;
 using System.Text.Json;
 using Spectre.Console;
 
@@ -46,7 +47,7 @@ internal static partial class CommandHandlers
         var driftResult = new DriftResultDto
         {
             Id = Guid.NewGuid().ToString("N")[..8],
-            ComparedAt = DateTimeOffset.UtcNow.ToString("O"),
+            ComparedAt = DateTimeOffset.UtcNow.ToString("O", CultureInfo.InvariantCulture),
             BaseGraphId = baseId,
             HeadGraphId = headId ?? "latest",
             Summary = new DriftSummaryDto
@@ -103,7 +104,7 @@ internal static partial class CommandHandlers
         var driftResult = new DriftResultDto
         {
             Id = id,
-            ComparedAt = DateTimeOffset.UtcNow.ToString("O"),
+            ComparedAt = DateTimeOffset.UtcNow.ToString("O", CultureInfo.InvariantCulture),
             BaseGraphId = "base",
             HeadGraphId = "head",
             Summary = new DriftSummaryDto