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.

docs/implplan/SPRINT_100_identity_signing.md

@@ -108,6 +108,7 @@ PLG7.IMPL-001 | DONE (2025-11-03) | Scaffold `StellaOps.Authority.Plugin.Ldap` +
 PLG7.IMPL-002 | DOING (2025-11-03) | Implement LDAP credential store with TLS/mutual TLS enforcement, deterministic retry/backoff, and structured logging/metrics. | BE-Auth Plugin, Security Guild (src/Authority/StellaOps.Authority/StellaOps.Authority.Plugin.Standard/TASKS.md)
 > 2025-11-03: Review concluded; RFC accepted with audit/mTLS/mapping decisions recorded in `docs/notes/2025-11-03-authority-plugin-ldap-review.md`. Follow-up implementation tasks PLG7.IMPL-001..005 added to plugin board.
 > 2025-11-04: Updated connection factory to negotiate StartTLS via `StartTransportLayerSecurity(null)` and normalized LDAP result-code handling (invalid credentials + transient codes) against `System.DirectoryServices.Protocols` 8.0. Plugin unit suite (`dotnet test src/Authority/StellaOps.Authority/StellaOps.Authority.Plugin.Ldap.Tests/StellaOps.Authority.Plugin.Ldap.Tests.csproj`) now passes again after the retry/error-path fixes.
+> 2025-11-04: PLG7.IMPL-002 progress – enforced TLS/client certificate validation, expanded LDAP audit properties and retry telemetry, warned when cipher lists are unsupported, refreshed sample config, and reran `dotnet test src/Authority/StellaOps.Authority/StellaOps.Authority.Plugin.Ldap.Tests/StellaOps.Authority.Plugin.Ldap.Tests.csproj --no-restore`.
 
 [Identity & Signing] 100.C) IssuerDirectory
 Summary: Identity & Signing focus on IssuerDirectory.
@@ -131,3 +132,6 @@ KMS-73-002 | TODO | Implement PKCS#11/HSM driver plus FIDO2 signing support for
 
 
 If all tasks are done - read next sprint section - SPRINT_110_ingestion_evidence.md
+
+
+