feat: wire Inbound API Route.To().Call() to site instance scripts and add Roslyn compilation

Completes the Inbound API → site script call chain by adding RouteToCallRequest
handlers in SiteCommunicationActor and DeploymentManagerActor. Also replaces the
placeholder dispatch table in InboundScriptExecutor with Roslyn compilation of
API method scripts at startup, enabling user-defined inbound API methods to call
instance scripts across the cluster.

src/ScadaLink.SiteRuntime/Actors/DeploymentManagerActor.cs

@@ -3,7 +3,9 @@ using Microsoft.Extensions.Logging;
 using ScadaLink.Commons.Messages.Artifacts;
 using ScadaLink.Commons.Messages.DebugView;
 using ScadaLink.Commons.Messages.Deployment;
+using ScadaLink.Commons.Messages.InboundApi;
 using ScadaLink.Commons.Messages.Lifecycle;
+using ScadaLink.Commons.Messages.ScriptExecution;
 using ScadaLink.Commons.Types.Enums;
 using ScadaLink.HealthMonitoring;
 using ScadaLink.SiteRuntime.Messages;
@@ -77,6 +79,9 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
         Receive<UnsubscribeDebugViewRequest>(RouteDebugViewUnsubscribe);
         Receive<DebugSnapshotRequest>(RouteDebugSnapshot);
 
+        // Inbound API Route.To().Call() — route to Instance Actors
+        Receive<RouteToCallRequest>(RouteInboundApiCall);
+
         // Internal startup messages
         Receive<StartupConfigsLoaded>(HandleStartupConfigsLoaded);
         Receive<StartNextBatch>(HandleStartNextBatch);
@@ -486,6 +491,41 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
         }
     }
 
+    // ── Inbound API routing ──
+
+    private void RouteInboundApiCall(RouteToCallRequest request)
+    {
+        if (_instanceActors.TryGetValue(request.InstanceUniqueName, out var instanceActor))
+        {
+            // Convert to ScriptCallRequest and Ask the Instance Actor
+            var scriptCall = new ScriptCallRequest(
+                request.ScriptName, request.Parameters, 0, request.CorrelationId);
+            var sender = Sender;
+            instanceActor.Ask<ScriptCallResult>(scriptCall, TimeSpan.FromSeconds(30))
+                .ContinueWith(t =>
+                {
+                    if (t.IsCompletedSuccessfully)
+                    {
+                        var result = t.Result;
+                        return new RouteToCallResponse(
+                            request.CorrelationId, result.Success, result.ReturnValue,
+                            result.ErrorMessage, DateTimeOffset.UtcNow);
+                    }
+                    return new RouteToCallResponse(
+                        request.CorrelationId, false, null,
+                        t.Exception?.GetBaseException().Message ?? "Script call timed out",
+                        DateTimeOffset.UtcNow);
+                }).PipeTo(sender);
+        }
+        else
+        {
+            Sender.Tell(new RouteToCallResponse(
+                request.CorrelationId, false, null,
+                $"Instance '{request.InstanceUniqueName}' not found on this site.",
+                DateTimeOffset.UtcNow));
+        }
+    }
+
     /// <summary>
     /// WP-33: Handles system-wide artifact deployment (shared scripts, external systems, etc.).
     /// Persists artifacts to SiteStorageService and recompiles shared scripts.