Server-side scenario execution: effects client replaces local engine

- client.Effects: typed effects + completion methods posting scenario callbacks
- client.Scenario reduced to TriggerAsync
- pending polling via Update() pump: 30s heartbeat + wait-deadline checks
- local engine, plan persistence (IPlanStateStore) and resume removed
- RealtimeService and realtime transports removed (relay never deployed)
- dead IPlanScheduler leftover removed
- models regenerated from openapi (ExecutionPlan/BoundaryNode gone, PendingEffect added)

RudderClientOptions.cs

@@ -12,9 +12,6 @@ public sealed class RudderClientOptions
     /// <summary>API base URL, e.g. https://api.example.com. Required.</summary>
     public string? BaseUrl { get; set; }
 
-    /// <summary>Realtime websocket URL. Required only for <see cref="RealtimeService"/>.</summary>
-    public string? RealtimeUrl { get; set; }
-
     /// <summary>Project key issued in the admin panel. Required.</summary>
     public string? ProjectKey { get; set; }
 
@@ -30,15 +27,6 @@ public sealed class RudderClientOptions
     /// <summary>Diagnostic sink. Null by default (silent).</summary>
     public IRudderLogger? Logger { get; set; }
 
-    /// <summary>Time source for the scenario runtime; override in tests.</summary>
+    /// <summary>Time source for the effects client; override in tests.</summary>
     public IClock? Clock { get; set; }
-
-    /// <summary>Scenario-run persistence between app launches. Optional.</summary>
-    public IPlanStateStore? PlanStateStore { get; set; }
-
-    /// <summary>Optional scheduler for delayed plan work.</summary>
-    public IPlanScheduler? Scheduler { get; set; }
-
-    /// <summary>Realtime transport factory. Required only for <see cref="RealtimeService"/>.</summary>
-    public IRealtimeTransportFactory? RealtimeTransportFactory { get; set; }
 }