feat(srp): add shader pass selection for scene draws

- let DrawingSettings carry an optional shaderPassName across managed and native scene draw APIs
- allow RenderObjectsRendererFeature to author explicit ForwardLit or Unlit scene draws
- exercise the new scene draw pass selection seam in the project render pipeline probe

engine/include/XCEngine/Rendering/Execution/DrawSettings.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <XCEngine/Core/Asset/ResourceHandle.h>
+#include <XCEngine/Core/Containers/String.h>
 #include <XCEngine/Rendering/Execution/ScenePhase.h>
 #include <XCEngine/Rendering/FrameData/CullingResults.h>
 #include <XCEngine/Resources/Material/Material.h>
@@ -12,10 +13,15 @@ struct DrawSettings {
     ScenePhase scenePhase = ScenePhase::Opaque;
     RendererListDesc rendererListDesc = {};
     Resources::ResourceHandle<Resources::Material> overrideMaterial = {};
+    Containers::String shaderPassName = {};
 
     bool HasOverrideMaterial() const {
         return overrideMaterial.IsValid();
     }
+
+    bool HasShaderPassName() const {
+        return !shaderPassName.Empty();
+    }
 };
 
 } // namespace Rendering

engine/include/XCEngine/Rendering/Pipelines/BuiltinForwardPipeline.h

@@ -297,10 +297,12 @@ private:
     void DestroyPipelineResources();
     static bool TryResolveSurfacePassType(
         const Resources::Material* material,
+        const BuiltinMaterialPass* preferredPass,
         BuiltinMaterialPass& outPass);
     ResolvedShaderPass ResolveSurfaceShaderPass(
         const RenderSceneData& sceneData,
-        const Resources::Material* material) const;
+        const Resources::Material* material,
+        const BuiltinMaterialPass* preferredPass) const;
     PassResourceLayout* GetOrCreatePassResourceLayout(
         const RenderContext& context,
         const ResolvedShaderPass& resolvedShaderPass);
@@ -308,7 +310,8 @@ private:
         const RenderContext& context,
         const RenderSurface& surface,
         const RenderSceneData& sceneData,
-        const Resources::Material* material);
+        const Resources::Material* material,
+        const BuiltinMaterialPass* preferredPass);
     RHI::RHIPipelineState* GetOrCreateSkyboxPipelineState(
         const RenderContext& context,
         const RenderSurface& surface);
@@ -364,7 +367,8 @@ private:
     bool DrawVisibleItem(
         const FrameExecutionContext& executionContext,
         const VisibleRenderItem& visibleItem,
-        const Resources::Material* material);
+        const Resources::Material* material,
+        const BuiltinMaterialPass* preferredPass);
     bool EnsureSkyboxResources(const RenderContext& context);
     bool CreateSkyboxResources(const RenderContext& context);
     void DestroySkyboxResources();