Merge branch 'feature/audit-actor-identity': populate audit Actor column

Stamp the audit Actor column on outbound rows (calling script identity) and
central-dispatch rows (system identity); the original emission code left it
null on every channel except Inbound API.

src/ScadaLink.NotificationOutbox/NotificationOutboxActor.cs

@@ -30,6 +30,13 @@ public class NotificationOutboxActor : ReceiveActor, IWithTimers
     private const int FallbackMaxRetries = 10;
     private static readonly TimeSpan FallbackRetryDelay = TimeSpan.FromMinutes(1);
 
+    /// <summary>
+    /// Audit <c>Actor</c> stamped on central-dispatch (<c>NotifyDeliver</c>) rows.
+    /// The Actor-column spec assigns central-originated audit rows a system
+    /// identity — there is no per-call authenticated user at dispatch time.
+    /// </summary>
+    private const string SystemActor = "system";
+
     private readonly IServiceProvider _serviceProvider;
     private readonly NotificationOutboxOptions _options;
     private readonly ICentralAuditWriter _auditWriter;
@@ -500,9 +507,11 @@ public class NotificationOutboxActor : ReceiveActor, IWithTimers
             Channel = AuditChannel.Notification,
             Kind = AuditKind.NotifyDeliver,
             CorrelationId = correlationId,
-            // Central dispatch — no authenticated actor (the originating
-            // script's identity is captured on the upstream NotifySend row).
-            Actor = null,
+            // Central dispatch — a system identity per the Actor-column spec;
+            // there is no per-call authenticated user here. The originating
+            // script is still captured on SourceScript (and on the upstream
+            // NotifySend row).
+            Actor = SystemActor,
             SourceSiteId = notification.SourceSiteId,
             SourceInstanceId = notification.SourceInstanceId,
             SourceScript = notification.SourceScript,

src/ScadaLink.SiteRuntime/Scripts/AuditingDbCommand.cs

@@ -430,7 +430,10 @@ internal sealed class AuditingDbCommand : DbCommand
             SourceSiteId = string.IsNullOrEmpty(_siteId) ? null : _siteId,
             SourceInstanceId = _instanceName,
             SourceScript = _sourceScript,
-            Actor = null,
+            // Outbound channel: per the Audit Log Actor-column spec the actor is
+            // the calling script. Null when no single script owns the call
+            // (e.g. a shared script running inline).
+            Actor = _sourceScript,
             Target = target,
             Status = status,
             HttpStatus = null,

src/ScadaLink.SiteRuntime/Scripts/ScriptRuntimeContext.cs

@@ -875,7 +875,10 @@ public class ScriptRuntimeContext
                 SourceSiteId = string.IsNullOrEmpty(_siteId) ? null : _siteId,
                 SourceInstanceId = _instanceName,
                 SourceScript = _sourceScript,
-                Actor = null,
+                // Outbound channel: per the Audit Log Actor-column spec the actor
+                // is the calling script. Null when no single script owns the call
+                // (e.g. a shared script running inline).
+                Actor = _sourceScript,
                 Target = $"{systemName}.{methodName}",
                 Status = status,
                 HttpStatus = httpStatus,
@@ -1355,7 +1358,10 @@ public class ScriptRuntimeContext
                     SourceSiteId = string.IsNullOrEmpty(_siteId) ? null : _siteId,
                     SourceInstanceId = _instanceName,
                     SourceScript = _sourceScript,
-                    Actor = null,
+                    // Outbound channel: per the Audit Log Actor-column spec the
+                    // actor is the calling script. Null when no single script
+                    // owns the call (e.g. a shared script running inline).
+                    Actor = _sourceScript,
                     Target = _listName,
                     Status = AuditStatus.Submitted,
                     HttpStatus = null,