refactor(srp): remove managed frame planning hook

- derive fullscreen stage planning from pipeline render-graph support
- trim planning-only APIs from the managed SRP bridge and public surface
- update probes and tests to lock the slimmer SRP API boundary

managed/XCEngine.ScriptCore/Rendering/Core/ScriptableRenderPipelineAsset.cs

@@ -18,11 +18,6 @@ namespace XCEngine.Rendering
         {
         }
 
-        protected virtual void ConfigureCameraFramePlan(
-            ScriptableRenderPipelinePlanningContext context)
-        {
-        }
-
         protected virtual FinalColorSettings GetDefaultFinalColorSettings()
         {
             return FinalColorSettings.CreateDefault();