feat(host): register SiteCallAuditActor + CachedCallTelemetry forwarder/bridge (#22, #23 M3)

M3 Bundle F (Task F1) wires the cached-call audit pipeline through the
composition roots:

- Central: register SiteCallAuditActor as a cluster singleton + proxy
  (mirrors AuditLogIngestActor and NotificationOutboxActor). Program.cs
  calls .AddSiteCallAudit() on the central role.
- Site: register ICachedCallTelemetryForwarder + CachedCallLifecycleBridge
  in AddAuditLog (lazy factory — Central nodes degrade to audit-only
  emission because IOperationTrackingStore is site-only).
- Site: bind CachedCallLifecycleBridge to ICachedCallLifecycleObserver so
  StoreAndForwardService picks it up via DI.
- Site: introduce IStoreAndForwardSiteContext + Host adapter to surface the
  site id to StoreAndForwardService without creating a
  StoreAndForward -> HealthMonitoring project-reference cycle.
- ScriptExecutionActor resolves ICachedCallTelemetryForwarder per script
  scope and threads it into ScriptRuntimeContext.

CachedCallTelemetryForwarder's IOperationTrackingStore dependency is now
nullable so Central DI validation succeeds with the lazy registration; the
forwarder's tracking-half emission is a no-op when the store is absent.

Tests:
- AkkaHostedServiceAuditWiringTests: Central host builds with
  AddSiteCallAudit and resolves ICachedCallTelemetryForwarder; Site
  resolves the forwarder + bridge + observer + IStoreAndForwardSiteContext.
- Full solution: 194 Host tests green, 241 SiteRuntime tests green, every
  other suite unchanged.

src/ScadaLink.SiteRuntime/Actors/ScriptExecutionActor.cs

@@ -111,6 +111,13 @@ public class ScriptExecutionActor : ReceiveActor
                 // that haven't wired the store, which the helper handles by
                 // throwing on access.
                 IOperationTrackingStore? operationTrackingStore = null;
+                // Audit Log #23 (M3 Bundle F — Task F1): site-side cached-call
+                // telemetry forwarder. Singleton bound to the AuditLog
+                // composition root; null in tests / hosts that haven't called
+                // AddAuditLog, in which case the cached-call helpers degrade
+                // to the no-emission path (the underlying S&F handoff still
+                // happens and a TrackedOperationId is still returned).
+                ICachedCallTelemetryForwarder? cachedForwarder = null;
 
                 if (serviceProvider != null)
                 {
@@ -122,6 +129,7 @@ public class ScriptExecutionActor : ReceiveActor
                         ?? string.Empty;
                     auditWriter = serviceScope.ServiceProvider.GetService<IAuditWriter>();
                     operationTrackingStore = serviceScope.ServiceProvider.GetService<IOperationTrackingStore>();
+                    cachedForwarder = serviceScope.ServiceProvider.GetService<ICachedCallTelemetryForwarder>();
                 }
 
                 var context = new ScriptRuntimeContext(
@@ -149,7 +157,14 @@ public class ScriptExecutionActor : ReceiveActor
                     // Audit Log #23 (M3 Bundle A — Task A3): site-local tracking store
                     // backing Tracking.Status(id). Authoritative source of truth for
                     // cached-call status — read directly by the script API.
-                    operationTrackingStore: operationTrackingStore);
+                    operationTrackingStore: operationTrackingStore,
+                    // Audit Log #23 (M3 Bundle F — Task F1): cached-call telemetry
+                    // forwarder for ExternalSystem.CachedCall / Database.CachedWrite
+                    // CachedSubmit emission + the immediate-success terminal-row
+                    // emission. Best-effort: null degrades the helpers to a
+                    // no-emission path; the S&F handoff and TrackedOperationId
+                    // return are unaffected.
+                    cachedForwarder: cachedForwarder);
 
                 var globals = new ScriptGlobals
                 {