Refactor and enhance LDAP plugin configuration and validation

- Updated `LdapPluginOptions` to enforce TLS and client certificate requirements.
- Added validation checks for TLS configuration in `LdapPluginOptionsTests`.
- Improved error handling in `DirectoryServicesLdapConnectionFactory` for StartTLS negotiation.
- Enhanced logging in `LdapCredentialStore` to include detailed audit properties for credential verification.
- Introduced `StubStructuredRetriever` and `StubVectorRetriever` for testing in `ToolsetServiceCollectionExtensionsTests`.
- Refactored `AdvisoryGuardrailPipelineTests` to improve test clarity and structure.
- Added `FileSystemAdvisoryTaskQueueTests` for testing queue functionality.
- Updated JSON test data for consistency with new requirements.
- Modified `AdvisoryPipelineOrchestratorTests` to reflect changes in metadata keys.

src/AdvisoryAI/StellaOps.AdvisoryAI/Guardrails/AdvisoryGuardrailPipeline.cs

@@ -21,7 +21,7 @@ public sealed record AdvisoryGuardrailResult(
     public static AdvisoryGuardrailResult Allowed(string sanitizedPrompt, ImmutableDictionary<string, string>? metadata = null)
         => new(false, sanitizedPrompt, ImmutableArray<AdvisoryGuardrailViolation>.Empty, metadata ?? ImmutableDictionary<string, string>.Empty);
 
-    public static AdvisoryGuardrailResult Blocked(string sanitizedPrompt, IEnumerable<AdvisoryGuardrailViolation> violations, ImmutableDictionary<string, string>? metadata = null)
+    public static AdvisoryGuardrailResult Reject(string sanitizedPrompt, IEnumerable<AdvisoryGuardrailViolation> violations, ImmutableDictionary<string, string>? metadata = null)
         => new(true, sanitizedPrompt, violations.ToImmutableArray(), metadata ?? ImmutableDictionary<string, string>.Empty);
 }
 
@@ -143,7 +143,7 @@ internal sealed class AdvisoryGuardrailPipeline : IAdvisoryGuardrailPipeline
         if (blocked)
         {
             _logger?.LogWarning("Guardrail blocked prompt for cache key {CacheKey}", prompt.CacheKey);
-            return Task.FromResult(AdvisoryGuardrailResult.Blocked(sanitized, violations, metadata));
+            return Task.FromResult(AdvisoryGuardrailResult.Reject(sanitized, violations, metadata));
         }
 
         return Task.FromResult(AdvisoryGuardrailResult.Allowed(sanitized, metadata));