feat(site-runtime): outbound API/DB/notification audit rows ride the flow-trace collector

ScriptRuntimeContext caches a trace sink (null on an untraced run, so the
production path is byte-identical) and threads it into the ExternalSystem /
Database / Notify helpers and AuditingDbConnection→AuditingDbCommand (onAudit).
All eight outbound emit sites hand the SAME AuditEvent instance to the sink
first, then to the writer/forwarder. FlowTraceCollector gains Completed +
Complete(): ScriptRunLauncher closes the collector where it builds the reply
snapshot, so un-awaited calls finishing after the run returned never mutate a
list the reply was built from. Cap (500) unchanged. Plan 2026-09-06 D5.

Claude-Session: https://claude.ai/code/session_01NcMG6xXdsJbmD2wYAgkK29

src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Scripts/AuditingDbConnection.cs

@@ -2,6 +2,7 @@ using System.Data;
 using System.Data.Common;
 using Microsoft.Extensions.Logging;
 using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Services;
+using AuditEvent = ZB.MOM.WW.Audit.AuditEvent;
 
 namespace ZB.MOM.WW.ScadaBridge.SiteRuntime.Scripts;
 
@@ -46,6 +47,13 @@ internal sealed class AuditingDbConnection : DbConnection
     /// </summary>
     private readonly Guid? _parentExecutionId;
 
+    /// <summary>
+    /// Flow Debugger (plan 2026-09-06 D5): optional observer handed the SAME
+    /// <see cref="AuditEvent"/> each <see cref="AuditingDbCommand"/> gives the writer —
+    /// the run's inline trace collector. Null when untraced.
+    /// </summary>
+    private readonly Action<AuditEvent>? _onAudit;
+
     private readonly ILogger _logger;
 
     /// <summary>
@@ -60,6 +68,7 @@ internal sealed class AuditingDbConnection : DbConnection
     /// <param name="logger">Logger for diagnostics and warnings.</param>
     /// <param name="executionId">Unique identifier for this script execution.</param>
     /// <param name="parentExecutionId">Optional identifier of the parent execution (for routed calls).</param>
+    /// <param name="onAudit">Optional observer of every emitted <see cref="AuditEvent"/> (the Flow Debugger trace collector).</param>
     // Parameter ordering: executionId sits immediately after the ILogger,
     // consistent with the other three audit-threaded ctors (ExternalSystemHelper,
     // DatabaseHelper, AuditingDbCommand). parentExecutionId is a trailing
@@ -73,7 +82,8 @@ internal sealed class AuditingDbConnection : DbConnection
         string? sourceScript,
         ILogger logger,
         Guid executionId,
-        Guid? parentExecutionId = null)
+        Guid? parentExecutionId = null,
+        Action<AuditEvent>? onAudit = null)
     {
         _inner = inner ?? throw new ArgumentNullException(nameof(inner));
         _auditWriter = auditWriter ?? throw new ArgumentNullException(nameof(auditWriter));
@@ -84,6 +94,7 @@ internal sealed class AuditingDbConnection : DbConnection
         _logger = logger ?? throw new ArgumentNullException(nameof(logger));
         _executionId = executionId;
         _parentExecutionId = parentExecutionId;
+        _onAudit = onAudit;
     }
 
     /// <summary>
@@ -155,7 +166,9 @@ internal sealed class AuditingDbConnection : DbConnection
             _executionId,
             // ParentExecutionId: the spawning execution's id,
             // threaded alongside _executionId. Null for non-routed runs.
-            _parentExecutionId);
+            _parentExecutionId,
+            // Flow Debugger: the DbWrite rows ride the inline collector.
+            _onAudit);
     }
 
     /// <inheritdoc />