feat(scripts): realign Test Run with runtime API, add anonymous-object calls and instance binding

The Test Run sandbox and Monaco analysis modelled a script API that had
drifted from the site runtime's ScriptGlobals, so real scripts failed to
compile in Test Run. Realign both to the runtime surface
(Instance/Scripts/ExternalSystem/Attributes/Children/Parent) and drop the
duplicate ScriptHost stub so the two cannot diverge again.

- Script calls (Scripts.CallShared, Instance.CallScript, Route.To().Call)
  accept an anonymous object instead of a hand-built dictionary, via a
  shared ScriptArgs normalizer; existing dictionary calls still compile.
- Test Run can optionally bind to a deployed instance, so Instance/
  Attributes/CallScript route to it cross-site; adds site-side
  RouteToGetAttributes/RouteToSetAttributes handlers.
- Adds Test Run panels to the API method and template script editors.
- Fixes the TestDatabaseQuery seed script, which queried a table that
  never existed.

Also commits unrelated in-progress work already in the tree: the health
monitoring report loop, site streaming changes, and the Admin/Design
data-connection and SMTP page reorganization.

src/ScadaLink.HealthMonitoring/CentralHealthAggregator.cs

@@ -47,6 +47,7 @@ public class CentralHealthAggregator : BackgroundService, ICentralHealthAggregat
                     SiteId = report.SiteId,
                     LatestReport = report,
                     LastReportReceivedAt = now,
+                    LastHeartbeatAt = now,
                     LastSequenceNumber = report.SequenceNumber,
                     IsOnline = true
                 };
@@ -64,6 +65,7 @@ public class CentralHealthAggregator : BackgroundService, ICentralHealthAggregat
                 var wasOffline = !existing.IsOnline;
                 existing.LatestReport = report;
                 existing.LastReportReceivedAt = now;
+                existing.LastHeartbeatAt = now;
                 existing.LastSequenceNumber = report.SequenceNumber;
                 existing.IsOnline = true;
 
@@ -86,8 +88,8 @@ public class CentralHealthAggregator : BackgroundService, ICentralHealthAggregat
         if (!_siteStates.TryGetValue(siteId, out var state))
             return;
 
-        if (receivedAt > state.LastReportReceivedAt)
-            state.LastReportReceivedAt = receivedAt;
+        if (receivedAt > state.LastHeartbeatAt)
+            state.LastHeartbeatAt = receivedAt;
 
         if (!state.IsOnline)
         {
@@ -141,12 +143,15 @@ public class CentralHealthAggregator : BackgroundService, ICentralHealthAggregat
             var state = kvp.Value;
             if (!state.IsOnline) continue;
 
-            var elapsed = now - state.LastReportReceivedAt;
+            // Use LastHeartbeatAt — heartbeats arrive every ~5s from any
+            // healthy site node, so OfflineTimeout only fires when no node
+            // can reach central, not during single-node failovers.
+            var elapsed = now - state.LastHeartbeatAt;
             if (elapsed > _options.OfflineTimeout)
             {
                 state.IsOnline = false;
                 _logger.LogWarning(
-                    "Site {SiteId} marked offline — no report for {Elapsed}s (timeout: {Timeout}s)",
+                    "Site {SiteId} marked offline — no signal for {Elapsed}s (timeout: {Timeout}s)",
                     state.SiteId, elapsed.TotalSeconds, _options.OfflineTimeout.TotalSeconds);
             }
         }