refactor: 解耦重构——还清四处架构债（对齐 UE/Unity 分层）

- SceneRenderer：场景→渲染数据翻译层（UE FSceneRenderer / Unity CullingResults
  模式），收口相机/灯光/光空间矩阵/双视图剔除，Renderer 只编排
- pass 对象化（Unity ScriptableRenderPass 模式）：8 个 pass lambda 拆为
  Passes::{Shadow,Forward,Bloom,Tonemap,ImGui,Present}，BuildGraph 超级函数消失；
  SceneGpu/FullscreenGpu 承接共享装配
- 中性 AssetRef（Core 层）：ECS 组件不再依赖 Assets 模块（Unity InstanceID 思路）
- IAssetUploader 接口：AssetManager 不感知 Vulkan 具体类，上传服务由渲染层
  VulkanAssetUploader 提供
- Renderer 公共 API 不变（App 层零改动），编译零错误 validation 零警告

Engine/src/Renderer/Passes/ImGuiPass.cpp

@@ -0,0 +1,36 @@
+//
+// Created by atdunbg on 2026/9/23.
+//
+
+#include <Engine/Renderer/Passes/ImGuiPass.h>
+#include <Engine/ImGui/ImGuiLayer.h>
+
+namespace Engine::Passes
+{
+    void ImGuiPass::Register(RG::RenderGraph& rg)
+    {
+        rg.AddPass("ImGui", [this](RG::RenderGraphContext& ctx) {
+            const vk::CommandBuffer cmd = ctx.cmd;
+
+            vk::RenderingAttachmentInfo colorAttachment;
+            colorAttachment.setImageView(ctx.View(m_Backbuffer))
+                           .setImageLayout(vk::ImageLayout::eColorAttachmentOptimal)
+                           .setLoadOp(vk::AttachmentLoadOp::eLoad)   // 关键：叠加
+                           .setStoreOp(vk::AttachmentStoreOp::eStore);
+
+            vk::RenderingInfo renderingInfo;
+            renderingInfo.setRenderArea({{0, 0}, ctx.extent})
+                         .setLayerCount(1)
+                         .setColorAttachments(colorAttachment);
+
+            cmd.beginRendering(renderingInfo);
+
+            if (*m_Layer) {
+                (*m_Layer)->RenderDrawData(cmd);
+            }
+
+            cmd.endRendering();
+        }).Write(m_Backbuffer, RG::ResourceUse::ColorAttachment);
+    }
+
+} // namespace Engine::Passes