fix(options): bind + validate OperationTrackingOptions; register the site IOperationTrackingStore that two comments claimed AddSiteRuntime provides (plan R2-08 T8, arch-review 08r2 NF4)

VERIFY-THEN-FIX: the plan-authoring discovery is CONFIRMED. No code anywhere in
src/ registered IOperationTrackingStore in DI, yet AkkaHostedService and
AuditLog SCE both comment that AddSiteRuntime provides it. Every consumer
resolved it via GetService (null-tolerant) and silently ran degraded:
cached-drain scheduler never armed, PullSiteCalls reconciliation seam never
wired, Tracking.Status degraded to audit-only. This is a FUNCTIONAL FIX riding
the hygiene plan: AddSiteRuntime now registers the store (site-only), so
site-local cached-call tracking runs in its intended mode. OperationTrackingOptions
is now bound + eagerly validated in the Host site-options block.

src/ZB.MOM.WW.ScadaBridge.Host/SiteServiceRegistration.cs

@@ -137,6 +137,18 @@ public static class SiteServiceRegistration
         services.TryAddEnumerable(
             ServiceDescriptor.Singleton<IValidateOptions<SiteRuntimeOptions>, SiteRuntimeOptionsValidator>());
 
+        // OperationTrackingOptions for the site-local cached-call tracking store
+        // (registered by AddSiteRuntime). Bind + eagerly validate here — the store
+        // opens its SQLite connection string at construction, so a blank connection
+        // string should fail the host at boot with a key-naming message rather than
+        // throw opaquely on first resolve (arch-review 08r2 NF4/T8).
+        services.AddOptions<SiteRuntime.Tracking.OperationTrackingOptions>()
+            .Bind(config.GetSection("ScadaBridge:OperationTracking"))
+            .ValidateOnStart();
+        services.TryAddEnumerable(
+            ServiceDescriptor.Singleton<IValidateOptions<SiteRuntime.Tracking.OperationTrackingOptions>,
+                SiteRuntime.Tracking.OperationTrackingOptionsValidator>());
+
         services.Configure<DataConnectionOptions>(config.GetSection("ScadaBridge:DataConnection"));
 
         services.AddOptions<StoreAndForwardOptions>()