feat(auditlog): site script-side emitters stamp ExecutionId

Move the per-script-execution Guid on ScriptRuntimeContext from
_auditCorrelationId to _executionId, and stamp it into the dedicated
AuditEvent.ExecutionId column on every script-side audit row:

- Sync ApiCall / DbWrite: ExecutionId set; CorrelationId reverts to
  null (a sync one-shot call has no operation lifecycle).
- Cached-call script-side rows (CachedSubmit, immediate-completion
  ApiCallCached + CachedResolve) and NotifySend: ExecutionId set;
  CorrelationId unchanged (per-operation TrackedOperationId /
  NotificationId).

Renames the threaded ctor param/field across ExternalSystemHelper,
DatabaseHelper, AuditingDbConnection and AuditingDbCommand, and threads
the id through NotifyHelper/NotifyTarget. The S&F retry-loop cached rows
(CachedCallLifecycleBridge) are out of scope here.

src/ScadaLink.SiteRuntime/Scripts/AuditingDbConnection.cs

@@ -36,10 +36,10 @@ internal sealed class AuditingDbConnection : DbConnection
     private readonly string _siteId;
     private readonly string _instanceName;
     private readonly string? _sourceScript;
-    private readonly Guid _auditCorrelationId;
+    private readonly Guid _executionId;
     private readonly ILogger _logger;
 
-    // Parameter ordering: auditCorrelationId sits immediately after the ILogger,
+    // Parameter ordering: executionId sits immediately after the ILogger,
     // consistent with the other three audit-threaded ctors (ExternalSystemHelper,
     // DatabaseHelper, AuditingDbCommand).
     public AuditingDbConnection(
@@ -50,7 +50,7 @@ internal sealed class AuditingDbConnection : DbConnection
         string instanceName,
         string? sourceScript,
         ILogger logger,
-        Guid auditCorrelationId)
+        Guid executionId)
     {
         _inner = inner ?? throw new ArgumentNullException(nameof(inner));
         _auditWriter = auditWriter ?? throw new ArgumentNullException(nameof(auditWriter));
@@ -59,7 +59,7 @@ internal sealed class AuditingDbConnection : DbConnection
         _instanceName = instanceName ?? string.Empty;
         _sourceScript = sourceScript;
         _logger = logger ?? throw new ArgumentNullException(nameof(logger));
-        _auditCorrelationId = auditCorrelationId;
+        _executionId = executionId;
     }
 
     // ConnectionString is settable on DbConnection — forward both halves.
@@ -99,7 +99,7 @@ internal sealed class AuditingDbConnection : DbConnection
             _instanceName,
             _sourceScript,
             _logger,
-            _auditCorrelationId);
+            _executionId);
     }
 
     protected override void Dispose(bool disposing)