test(secrets): fix Windows failures - skippable permission tests, release SQLite pools before delete (scadaproj#27)

The two Unix-permission tests called Skip.IfNot from a plain [Fact] (xunit v2 +
Xunit.SkippableFact) so they failed on Windows; now [SkippableFact].
Resolver_Works_EndToEnd_ThroughDi calls SqliteConnection.ClearAllPools() before
deleting its temp DB.

Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV

ZB.MOM.WW.Secrets/tests/ZB.MOM.WW.Secrets.Tests/Cli/Interactive/Flows/BundleFlowTests.cs

@@ -232,7 +232,7 @@ public sealed class BundleFlowTests : IDisposable
         Assert.Null(await target.Store.GetAsync(new SecretName("svc/cross"), CancellationToken.None)); // untouched
     }
 
-    [Fact]
+    [SkippableFact]
     public async Task Import_source_key_file_permission_denied_renders_friendly_error_without_importing()
     {
         Skip.IfNot(!OperatingSystem.IsWindows(), "Unix permission bits are exercised via UnixFileMode.");

ZB.MOM.WW.Secrets/tests/ZB.MOM.WW.Secrets.Tests/Cli/Interactive/Flows/KekDoctorFlowTests.cs

@@ -226,7 +226,7 @@ public sealed class KekDoctorFlowTests : IAsyncLifetime, IDisposable
         Assert.Equal(_kekA.KekId, (await GetAsync("svc/a")).KekId); // nothing changed
     }
 
-    [Fact]
+    [SkippableFact]
     public async Task File_old_key_source_permission_denied_renders_friendly_error_and_still_re_diagnoses()
     {
         Skip.IfNot(!OperatingSystem.IsWindows(), "Unix permission bits are exercised via UnixFileMode.");

ZB.MOM.WW.Secrets/tests/ZB.MOM.WW.Secrets.Tests/DependencyInjection/AddZbSecretsTests.cs

@@ -116,6 +116,8 @@ public sealed class AddZbSecretsTests
         finally
         {
             Environment.SetEnvironmentVariable(envVar, null);
+            // Pooled SQLite handles keep the file open (Windows cannot delete it) - release them first.
+            Microsoft.Data.Sqlite.SqliteConnection.ClearAllPools();
             File.Delete(dbPath);
         }
     }