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)

Abstractions/IClock.cs

@@ -2,7 +2,7 @@ using System;
 
 namespace RudderSdk.Core.Abstractions;
 
-/// <summary>Time source used by the scenario runtime; override in tests.</summary>
+/// <summary>Time source used by the effects client; override in tests.</summary>
 public interface IClock
 {
     /// <summary>Current UTC time.</summary>

Abstractions/IPlanScheduler.cs

@@ -1,12 +0,0 @@
-using System;
-using System.Threading;
-using System.Threading.Tasks;
-
-namespace RudderSdk.Core.Abstractions;
-
-/// <summary>Optional scheduler abstraction for delayed plan work.</summary>
-public interface IPlanScheduler
-{
-    /// <summary>Completes after the given delay.</summary>
-    Task ScheduleAsync(TimeSpan delay, CancellationToken cancellationToken = default);
-}

Abstractions/IPlanStateStore.cs

@@ -1,11 +0,0 @@
-namespace RudderSdk.Core.Abstractions;
-
-/// <summary>
-/// Persists serialized scenario-run state between app launches.
-/// Null by default (no persistence).
-/// </summary>
-public interface IPlanStateStore
-{
-    /// <summary>Serialized state blob, or null when empty.</summary>
-    string? State { get; set; }
-}

Abstractions/IRealtimeTransport.cs

@@ -1,36 +0,0 @@
-using System;
-using System.Threading;
-using System.Threading.Tasks;
-
-namespace RudderSdk.Core.Abstractions;
-
-/// <summary>
-/// Low-level realtime (websocket) transport. There is no default implementation;
-/// provide one through <see cref="IRealtimeTransportFactory"/> (Unity ships its own).
-/// </summary>
-public interface IRealtimeTransport
-{
-    /// <summary>Raised when the connection closes.</summary>
-    event Action Closed;
-
-    /// <summary>Raised for every incoming message.</summary>
-    event Action<ArraySegment<byte>> Received;
-
-    /// <summary>Raised on transport errors.</summary>
-    event Action<Exception> Error;
-
-    /// <summary>True while the connection is open.</summary>
-    bool IsConnected { get; }
-
-    /// <summary>Opens the connection, giving up after <paramref name="timeout"/>.</summary>
-    Task ConnectAsync(Uri uri, TimeSpan timeout, CancellationToken cancellationToken = default);
-
-    /// <summary>Sends one message.</summary>
-    Task SendAsync(ArraySegment<byte> data, CancellationToken cancellationToken = default);
-
-    /// <summary>Closes the connection.</summary>
-    Task CloseAsync(CancellationToken cancellationToken = default);
-
-    /// <summary>Pumps time-dependent logic; call every frame.</summary>
-    void Update(float deltaTime);
-}

Abstractions/IRealtimeTransportFactory.cs

@@ -1,8 +0,0 @@
-namespace RudderSdk.Core.Abstractions;
-
-/// <summary>Creates realtime transports on demand (one per connection).</summary>
-public interface IRealtimeTransportFactory
-{
-    /// <summary>Creates a new, unconnected transport.</summary>
-    IRealtimeTransport Create();
-}