feat(srp): add renderer-driven pipeline backbone

Introduce renderer-driven and renderer-backed managed pipeline base types in the Universal package.

Move shared renderer-data/default-renderer ownership out of UniversalRenderPipelineAsset, migrate probe assets onto the generic seam, and expose renderer recording/request context types for future SRP expansion.

Update scripting API-surface expectations and validate with build, unit tests, scripting tests, and old editor smoke.

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

@@ -77,6 +77,22 @@ namespace XCEngine.Rendering.Universal
         {
         }
 
+        internal bool SupportsRendererRecording(
+            RendererRecordingContext context)
+        {
+            return context != null &&
+                   SupportsStageRenderGraph(context.stage);
+        }
+
+        internal bool RecordRenderer(
+            RendererRecordingContext context)
+        {
+            return context != null &&
+                   context.renderContext != null &&
+                   RecordStageRenderGraph(
+                       context.renderContext);
+        }
+
         protected internal virtual bool SupportsStageRenderGraph(
             CameraFrameStage stage)
         {