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/RendererCameraRequestContext.cs

@@ -0,0 +1,28 @@
+using XCEngine.Rendering;
+
+namespace XCEngine.Rendering.Universal
+{
+    public sealed class RendererCameraRequestContext
+    {
+        private readonly CameraRenderRequestContext m_requestContext;
+
+        internal RendererCameraRequestContext(
+            CameraRenderRequestContext requestContext)
+        {
+            m_requestContext = requestContext;
+        }
+
+        public int renderedBaseCameraCount =>
+            m_requestContext != null
+                ? m_requestContext.renderedBaseCameraCount
+                : 0;
+
+        public int renderedRequestCount =>
+            m_requestContext != null
+                ? m_requestContext.renderedRequestCount
+                : 0;
+
+        internal CameraRenderRequestContext requestContext =>
+            m_requestContext;
+    }
+}