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/CentralHealthReportLoop.cs

@@ -0,0 +1,82 @@
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+
+namespace ScadaLink.HealthMonitoring;
+
+/// <summary>
+/// Central-side counterpart to <see cref="HealthReportSender"/>.
+/// Periodically builds a SiteHealthReport for the central cluster itself
+/// (siteId = <see cref="CentralSiteId"/>) and feeds it into the local
+/// CentralHealthAggregator so the UI can render central as another card
+/// on /monitoring/health. Only the cluster leader (Primary) generates
+/// reports — the standby's aggregator catches up on failover when it
+/// becomes Primary and starts its own loop.
+/// </summary>
+public class CentralHealthReportLoop : BackgroundService
+{
+    /// <summary>
+    /// Reserved siteId used to represent the central cluster in the
+    /// shared CentralHealthAggregator keyspace.
+    /// </summary>
+    public const string CentralSiteId = "central";
+
+    private readonly ISiteHealthCollector _collector;
+    private readonly ICentralHealthAggregator _aggregator;
+    private readonly IClusterNodeProvider _clusterNodeProvider;
+    private readonly HealthMonitoringOptions _options;
+    private readonly ILogger<CentralHealthReportLoop> _logger;
+
+    // Seeded with Unix-ms so reports from a newly-elected central leader
+    // always sort after reports from any prior leader for siteId="central".
+    private long _sequenceNumber = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds();
+
+    public CentralHealthReportLoop(
+        ISiteHealthCollector collector,
+        ICentralHealthAggregator aggregator,
+        IClusterNodeProvider clusterNodeProvider,
+        IOptions<HealthMonitoringOptions> options,
+        ILogger<CentralHealthReportLoop> logger)
+    {
+        _collector = collector;
+        _aggregator = aggregator;
+        _clusterNodeProvider = clusterNodeProvider;
+        _options = options.Value;
+        _logger = logger;
+    }
+
+    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+    {
+        _logger.LogInformation(
+            "Central health report loop starting, interval {Interval}s",
+            _options.ReportInterval.TotalSeconds);
+
+        using var timer = new PeriodicTimer(_options.ReportInterval);
+
+        while (await timer.WaitForNextTickAsync(stoppingToken).ConfigureAwait(false))
+        {
+            try
+            {
+                var isPrimary = _clusterNodeProvider.SelfIsPrimary;
+                _collector.SetActiveNode(isPrimary);
+
+                if (!isPrimary)
+                    continue;
+
+                _collector.SetClusterNodes(_clusterNodeProvider.GetClusterNodes());
+
+                var seq = Interlocked.Increment(ref _sequenceNumber);
+                var report = _collector.CollectReport(CentralSiteId);
+                var reportWithSeq = report with { SequenceNumber = seq };
+
+                _aggregator.ProcessReport(reportWithSeq);
+
+                _logger.LogDebug("Generated central health report #{Seq}", seq);
+            }
+            catch (Exception ex)
+            {
+                _logger.LogError(ex, "Failed to generate central health report");
+            }
+        }
+    }
+}