refactor(auditlog): rename audit correlation field, add cross-helper tests

src/ScadaLink.InboundAPI/Middleware/AuditWriteMiddleware.cs

@@ -148,6 +148,13 @@ public sealed class AuditWriteMiddleware
                 // Audit Log #23: a fresh per-request correlation 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
+                // 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(),
                 Actor = actor,
                 Target = methodName,