feat(historian): SQL Server retention purge (RetentionDays, Primary-gated, applock) (#667)

src/Server/ZB.MOM.WW.OtOpcUa.Host/Program.cs

@@ -326,6 +326,14 @@ if (hasDriver)
         builder.Services.AddSingleton<IHistorianValueWriter>(sp => sp.GetRequiredService<IHistorianBackendProvider>().CreateValueWriter(sp));
     }
 
+    // Historian retention (#667). Only a backend that manages retention in-process returns a purger
+    // (SqlServer with RetentionDays set); otherwise the service is inert. Primary-gated via IHistorizationRoleView.
+    if (serverHistorianOptions.Enabled)
+        builder.Services.AddHostedService(sp => new HistorianRetentionService(
+            sp.GetRequiredService<IHistorianBackendProvider>().CreateRetention(sp),
+            sp.GetService<ZB.MOM.WW.OtOpcUa.Runtime.Redundancy.IHistorizationRoleView>(),
+            sp.GetService<ILogger<HistorianRetentionService>>()));
+
     // Bind every cross-platform driver factory before AddAkka resolves IDriverFactory — replaces
     // the F7-default NullDriverFactory with a real DriverFactoryRegistryAdapter so DriverHostActor
     // can materialise real IDriver instances on deploy.