refactor(srp): add managed lifecycle cleanup seams

Invoke managed pipeline disposal and asset runtime cleanup from the native bridge lifecycle. Add Universal renderer and feature cleanup hooks plus regression probes to verify runtime cache teardown semantics.

managed/XCEngine.ScriptCore/Rendering/Universal/ScriptableRendererData.cs

@@ -38,6 +38,35 @@ namespace XCEngine.Rendering.Universal
             return GetPipelineRendererAssetKey();
         }
 
+        internal void ReleaseRuntimeResourcesInstance()
+        {
+            if (m_rendererInstance != null)
+            {
+                m_rendererInstance.ReleaseRuntimeResourcesInstance();
+                m_rendererInstance = null;
+                m_rendererFeatures = null;
+                ReleaseRuntimeResources();
+                return;
+            }
+
+            if (m_rendererFeatures != null)
+            {
+                for (int i = 0; i < m_rendererFeatures.Length; ++i)
+                {
+                    ScriptableRendererFeature rendererFeature =
+                        m_rendererFeatures[i];
+                    if (rendererFeature != null)
+                    {
+                        rendererFeature.ReleaseRuntimeResourcesInstance();
+                    }
+                }
+
+                m_rendererFeatures = null;
+            }
+
+            ReleaseRuntimeResources();
+        }
+
         internal void ConfigureCameraRenderRequestInstance(
             CameraRenderRequestContext context)
         {
@@ -80,6 +109,10 @@ namespace XCEngine.Rendering.Universal
             return Array.Empty<ScriptableRendererFeature>();
         }
 
+        protected virtual void ReleaseRuntimeResources()
+        {
+        }
+
         protected bool HasDirectionalShadow(
             CameraRenderRequestContext context)
         {