fix(secrets-ui): preserve metadata on rotate + audit unexpected mutation/reveal failures

ZB.MOM.WW.Secrets/src/ZB.MOM.WW.Secrets.Abstractions/ISecretActorAccessor.cs

@@ -3,15 +3,17 @@ namespace ZB.MOM.WW.Secrets.Abstractions;
 /// <summary>
 /// Resolves the current principal (the ZB.MOM.WW.Auth identity) for audit attribution when a
 /// secret is resolved. A consumer wires this to whatever surfaces the ambient caller — an HTTP
-/// context accessor, an actor context, a CLI identity, etc. A <c>null</c> <see cref="CurrentActor"/>
-/// (or no accessor at all) is treated as the <c>"system"</c> actor by the resolver, so keyless /
-/// background resolutions are still attributed rather than left blank.
+/// context accessor, an actor context, a CLI identity, etc. When <see cref="CurrentActor"/> is
+/// <c>null</c> (or no accessor is registered), the fallback actor string is consumer-defined so an
+/// action is still attributed rather than left blank — e.g. <c>"system"</c> for background/keyless
+/// resolution, or <c>"unknown"</c> for an unauthenticated UI action (the value the UI's
+/// <c>SecretActorResolver</c> uses).
 /// </summary>
 public interface ISecretActorAccessor
 {
     /// <summary>
     /// The current principal to record as the audit <c>Actor</c>, or <c>null</c> when no
-    /// principal is available (treated as <c>"system"</c>).
+    /// principal is available (the resolver then substitutes its consumer-defined fallback actor).
     /// </summary>
     string? CurrentActor { get; }
 }