Resolve all 33 medium-severity architecture review findings

Second slice of the 2026-09-09 whole-system review remediation
(docs/plans/2026-09-09-arch-review.md §10), on top of the High slice 146a1323.

Runtime/devices: SR-2 alarm on-trigger integration scope; SR-3 correlated NativeAlarmActor
subscribe retry; SR-4 immutable audited DB target; SR-5 ordered InstanceActor stop/flush;
SR-12 rehydration fence; SR-13 S&F gate recheck per delivery; DC-4 no OPC UA security
downgrade; DC-5 alarm snapshot for every new subscriber; ORCH-1 sync-dispose joins the pump.

Management/UI: MG-2 site scope on audit tree + Flow Debugger Replay; MG-3 stale-probe memo
removed; MG-4 server-owned bulk-deploy deadline; UI-5 sandbox runs in a killable child
process (new CentralUI.SandboxWorker project); UI-14 bounded sandbox output/IPC.

Edge/audit: EI-1 relay audit ownership; EI-2 SkipBodyCapture suppresses error text; EI-3/EI-11
error-field redaction + caps; EI-4 single relay deadline, pre-execution-only retry; EI-5
authenticated relay provenance; EI-10 body cap before audit read.

Persistence/contracts: DL-1 global Instance.UniqueName unique index + conflict translation;
DL-2 DataConnection protocol config encrypted at rest (migration
20260909203046_EnforceGlobalInstanceNamesAndProtectProtocolConfiguration — coordinated
central upgrade, old binaries cannot read protected rows); DL-3 bounded Replay paging;
DL-6 cross-site Overwrite of a deployed instance rejected; XC-4 proto descriptor contract test.

Config/hygiene: XC-1 central listener isolation by local port; XC-2/XC-3 inert SMTP + cron
keys removed from rig settings; CM-2 env2 bootstrap guard enabled; DC-6 deploy site exit code;
DC-7 notifier retries only explicit standby rejection; XC-5 ClusterClient purged from docs.

Gates recorded in the report: build 0/0, 9 397 passed / 0 failed, rig redeployed on all
eight nodes with the migration applied. 46 Low findings remain open.

src/ZB.MOM.WW.ScadaBridge.InboundAPI/RouteHelper.cs

@@ -240,14 +240,14 @@ public class RouteHelper
 
     /// <summary>
     /// Arch-review F11: returns a <see cref="RouteHelper"/> whose always-on <c>RouteCall</c> row
-    /// carries no request/response summary when <paramref name="captureBodies"/> is <c>false</c>.
+    /// carries no request/response summary or free-text error when <paramref name="captureBodies"/> is <c>false</c>.
     /// <see cref="InboundScriptExecutor"/> sets this from the executing method's
     /// <c>AuditLogOptions.PerTargetOverrides[method.Name].SkipBodyCapture</c> — the same override
     /// <c>AuditWriteMiddleware</c> honours for the inbound row — so an operator who suppressed a
     /// method's body from the audit log doesn't get it back via the routed call's arguments
     /// (which are derived from that same body). Default <c>true</c> (unchanged behaviour).
     /// </summary>
-    /// <param name="captureBodies">False to omit the request/response summary on the <c>RouteCall</c> row.</param>
+    /// <param name="captureBodies">False to omit request/response summaries and free-text errors on the <c>RouteCall</c> row.</param>
     /// <returns>A new <see cref="RouteHelper"/> carrying the flag.</returns>
     public RouteHelper WithBodyCapture(bool captureBodies) =>
         new(_instanceLocator, _instanceRouter, _deadlineToken, _requestAbortedToken, _parentExecutionId,
@@ -416,7 +416,7 @@ public class RouteTarget
                 executionId: _parentExecutionId,
                 parentExecutionId: null,
                 durationMs: (int)Math.Min(elapsedMs, int.MaxValue),
-                errorMessage: error,
+                errorMessage: _captureBodies ? error : null,
                 // Arch-review F11: a method with SkipBodyCapture set must not leak the routed
                 // call's arguments (derived from the same request body) or its return value.
                 requestSummary: _captureBodies ? TraceJson(args) : null,