feat(auditlog): inbound audit rows carry ExecutionId

src/ScadaLink.InboundAPI/Middleware/AuditWriteMiddleware.cs

@@ -145,17 +145,21 @@ public sealed class AuditWriteMiddleware
                 OccurredAtUtc = DateTime.UtcNow,
                 Channel = AuditChannel.ApiInbound,
                 Kind = kind,
-                // Audit Log #23: a fresh per-request correlation id so the
+                // Audit Log #23: a fresh per-request execution id so the
                 // inbound row carries a request identifier (closes the design
                 // gap that inbound rows should be correlatable).
                 //
                 // This id is intentionally request-local: it is NOT bridged to
                 // RouteHelper's routed-call correlation id or to
                 // HttpContext.TraceIdentifier. Threading an inbound request's
-                // correlation id through to the routed script execution (so an
+                // execution id through to the routed script execution (so an
                 // inbound call and the outbound API/DB rows it triggers share
                 // one id) is a deliberate future follow-up, out of scope here.
-                CorrelationId = Guid.NewGuid(),
+                ExecutionId = Guid.NewGuid(),
+                // CorrelationId is purely the per-operation-lifecycle id; an
+                // inbound request is a one-shot from the audit row's
+                // perspective with no multi-row operation to correlate.
+                CorrelationId = null,
                 Actor = actor,
                 Target = methodName,
                 Status = status,