Reorganize directory layout: editor panels/, grouped shaders, drop stale header

- App/editor: move 7 panels into panels/ (Editor core stays at root)
- shaders/: group into pbr/ post/ debug/ env/ (runtime load paths updated)
- Delete outdated duplicate Engine/src/Renderer/VulkanAssetUploader.h

shaders/env/skybox.frag

@@ -0,0 +1,21 @@
+#version 450
+
+// 天空盒像素：NDC → 世界方向 → cube 采样。
+// invVP = inverse(projNoJitter × mat4(mat3(view)))：去掉平移的视图，
+// 反投影结果即"相机相对"的世界方向，normalize 后直接采样 cube。
+
+layout(location = 0) in vec2 fragUV;
+layout(location = 0) out vec4 outColor;
+
+layout(set = 0, binding = 0) uniform samplerCube envMap;
+
+// push 与 skybox.vert 一致声明（VUID-08878）
+layout(push_constant) uniform PushConstants {
+    mat4 invVP;
+} pc;
+
+void main() {
+    vec4 target = pc.invVP * vec4(fragUV * 2.0 - 1.0, 1.0, 1.0);
+    vec3 dir = normalize(target.xyz / target.w);
+    outColor = vec4(texture(envMap, dir).rgb, 1.0);
+}