fix(health-monitoring): resolve HealthMonitoring-013,014,016 — shorter-timeout cadence, options validation, injected TimeProvider; HealthMonitoring-015 left open (cross-module design decision)

src/ScadaLink.HealthMonitoring/SiteHealthCollector.cs

@@ -23,6 +23,18 @@ public class SiteHealthCollector : ISiteHealthCollector
     private volatile string _nodeHostname = "";
     private volatile IReadOnlyList<Commons.Messages.Health.NodeStatus>? _clusterNodes;
     private volatile bool _isActiveNode;
+    private readonly TimeProvider _timeProvider;
+
+    /// <summary>
+    /// Creates a collector. The <paramref name="timeProvider"/> stamps each
+    /// report's timestamp; it defaults to <see cref="TimeProvider.System"/> and
+    /// is injectable so the report timestamp is deterministically testable —
+    /// consistent with the rest of the module's time-dependent classes.
+    /// </summary>
+    public SiteHealthCollector(TimeProvider? timeProvider = null)
+    {
+        _timeProvider = timeProvider ?? TimeProvider.System;
+    }
 
     /// <summary>
     /// Increment the script error counter. Covers unhandled exceptions,
@@ -148,7 +160,7 @@ public class SiteHealthCollector : ISiteHealthCollector
         return new SiteHealthReport(
             SiteId: siteId,
             SequenceNumber: 0, // Caller (HealthReportSender) assigns the sequence number
-            ReportTimestamp: DateTimeOffset.UtcNow,
+            ReportTimestamp: _timeProvider.GetUtcNow(),
             DataConnectionStatuses: connectionStatuses,
             TagResolutionCounts: tagResolution,
             ScriptErrorCount: scriptErrors,