fix: animation-only FBX assets loadable; clip data viewer

Pure-animation FBX (no meshes, skeleton clips only) was rejected at
the cache layer: ParsedModel::Valid() required non-empty meshes, so
Model::FromParsed/LoadModel returned null and the asset never made it
into the cache. Animation assets are now first-class:

- ParsedModel::Valid() = meshes or clips non-empty; parse failures
  (both empty) still rejected. Empty-mesh consumers already guarded
  (rendering skips empty mesh loop, mesh collider falls back to Box)
- ParseFromDisk: fix null-deref when assimp returns a null scene
- AssetCache::Find(path) + AssetManager::GetModelByPath for panels
- Asset Browser hover card shows meshes/bones/clips for loaded models
- Inspector model line flags "animation-only" when meshes == 0
- Animation section: collapsible clip data table (name/duration/
  channel count) to verify bone-name matching of attached clips

Engine/include/Engine/Assets/AssetManager.h

@@ -117,6 +117,17 @@ namespace Engine
                 return (e.generation == h.generation && e.alive) ? e.path : kEmpty;
             }
 
+            // 按路径查活资产（未加载/已卸载返回 nullptr；不触发加载、
+            // 不对坏句柄 FATAL）——面板展示用
+            T* Find(const std::string& path) const
+            {
+                auto it = m_ByPath.find(path);
+                if (it == m_ByPath.end()) return nullptr;
+                const Entry& e = m_Entries[it->second.index];
+                return (e.alive && e.generation == it->second.generation)
+                           ? e.asset.get() : nullptr;
+            }
+
             u32 Count() const
             {
                 return static_cast<u32>(m_Entries.size()) - static_cast<u32>(m_Free.size());
@@ -160,6 +171,12 @@ namespace Engine
             ModelRef LoadModel(const std::string& path, ParsedModel&& parsed);
             Model* GetModel(ModelRef h) const { return m_Models.Get(h); }
             void UnloadModel(ModelRef h) { m_Models.Unload(h); }
+            // 按路径查已加载的模型（未加载返回 null，不触发加载）——
+            // 面板 hover 信息卡用
+            Model* GetModelByPath(const std::string& path) const
+            {
+                return m_Models.Find(path);
+            }
 
             // ---- 外部动画并入（UE AnimSequence 归属 Skeleton 的简化版）----
             // 把动画容器文件（无网格 FBX/GLB 等）里的 clip 按骨骼节点名

Engine/include/Engine/Renderer/Model.h

@@ -99,7 +99,10 @@ namespace Engine
         std::vector<ModelNode> nodes;
         std::vector<ModelBone> bones;
         std::vector<AnimationClip> clips;
-        bool Valid() const { return !meshes.empty(); }
+        // 解析有效性：mesh 与 clip 至少其一非空。纯动画 FBX（无网格只有
+        // 骨骼动画，UE 的 Animation Sequence 资产同理）是合法资产——
+        // 过去只认 meshes 导致动画源文件在缓存层被整体拒载
+        bool Valid() const { return !meshes.empty() || !clips.empty(); }
     };
 
     class Model

Engine/src/Assets/AssetManager.cpp

@@ -140,8 +140,9 @@ namespace Engine::Assets {
                 return res;
             }
         }
-        // 纯 CPU 解析：动画容器只要 nodes + clips，不建 GPU 资产
-        //（meshes 空的文件过不了 Model 构建，也不需要构建）
+        // 纯 CPU 解析：动画容器只要 nodes + clips。不复用缓存里可能已
+        // 预热的同名 Model——缓存实例的 clips nodeIdx 按它自己的 node 表
+        // 编号，attach 需要按目标模型的 node 表重映射，必须独立解析
         ParsedModel src = Model::ParseFromDisk(animPath);
         if (src.clips.empty()) {
             ENGINE_WARN("AttachAnimationClips: no clips in '{}'", animPath);

Engine/src/Renderer/Model.cpp

@@ -194,7 +194,8 @@ ParsedModel Model::ParseFromDisk(const std::string& path)
         aiProcess_LimitBoneWeights);   // 每顶点限 4 权重（= 顶点格式 boneIds 容量）
 
     if (!scene || (scene->mFlags & AI_SCENE_FLAGS_INCOMPLETE) || !scene->mRootNode) {
-        if (!scene->mNumMeshes) {
+        // scene 可能为 null（文件损坏/格式不支持），先判空再打印资产清单
+        if (scene != nullptr) {
             ENGINE_WARN("Assimp warn: model dose not have mesh assets\nmodel has following asset:");
 
             ENGINE_WARN("\tMeshes Count: {}", scene->mNumMeshes);
@@ -204,10 +205,9 @@ ParsedModel Model::ParseFromDisk(const std::string& path)
             ENGINE_WARN("\tMaterials Count: {}", scene->mNumMaterials);
             ENGINE_WARN("\tSkeletons Count: {}", scene->mNumSkeletons);
             ENGINE_WARN("\tTextures Count: {}", scene->mNumTextures);
-
         }
         ENGINE_ERROR("Assimp error: {}", importer.GetErrorString());
-        return out;   // meshes 空 = 无效
+        return out;   // meshes/clips 空 = 无效
     }
 
     // 骨骼动画三件套：node 表（global 累乘骨架）→ 动画轨道 → 骨骼注册