Align RenderGraph imported texture ownership

engine/include/XCEngine/Rendering/AGENTS.md

@@ -143,6 +143,7 @@ native RenderGraph 当前支持：
 - 执行阶段通过 `RenderGraphExecutionContext` 解析 view 和 texture desc。
 - Graph-managed surface 必须关闭 `RenderSurface::autoTransition`，让 graph 统一负责 transition。
 - imported surface 的 transition ownership 只能通过 `RenderGraphImportedTextureOptions` 表达，不要在 pass 内外重复 barrier。
+- imported texture 的资源身份是 `RHITexture*`，不是某个 primary view。需要 graph 管理 transition 时，必须通过 `RenderGraphImportedTextureDesc.texture` 显式给出资源；`primaryView` 只能作为默认访问 view。surface import registry 应优先按 texture 合并，只有拿不到 texture 的非 graph-owned legacy/view-only import 才能退回按 view 区分。
 - fullscreen chain 中间输出优先使用 transient texture，不要把后处理链硬绑到 backbuffer。
 
 ## 6. Builtin Forward

engine/include/XCEngine/Rendering/Graph/RenderGraph.h

@@ -83,6 +83,10 @@ public:
 
     void Reset();
 
+    RenderGraphTextureHandle ImportTexture(
+        const Containers::String& name,
+        const RenderGraphImportedTextureDesc& importedDesc);
+
     RenderGraphTextureHandle ImportTexture(
         const Containers::String& name,
         const RenderGraphTextureDesc& desc,

engine/include/XCEngine/Rendering/Graph/RenderGraphTypes.h

@@ -92,6 +92,13 @@ struct RenderGraphImportedTextureOptions {
     bool graphOwnsTransitions = false;
 };
 
+struct RenderGraphImportedTextureDesc {
+    RenderGraphTextureDesc textureDesc = {};
+    RHI::RHITexture* texture = nullptr;
+    RHI::RHIResourceView* primaryView = nullptr;
+    RenderGraphImportedTextureOptions options = {};
+};
+
 struct RenderGraphTextureTransitionPlan {
     bool graphOwnsTransitions = false;
     bool hasFirstAccessState = false;