Add new node asset scripts for geometry and shader operations

- Implemented `build_mesh_plane.py` to create a geometry node group for mesh planes with customizable parameters.
- Created `build_shadeless.py` for a shader node group that displays color without scene lighting while preserving shadows and reflections.
- Added `validate.py` to validate the integrity of the newly created node groups and their inputs.
- Introduced `validate_cutout.py` to ensure the functionality of cutout node groups and their dependencies.
- Developed `validate_mesh_plane.py` to test the mesh plane creation and its modifier settings.

docs/internals/operators/debug.md

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+# Debug Operator
+
+本页对应 `src/anyimage/operators/debug.py`。这些 Operator 为开发者直接验证 DA3、MoGe-2、BEN2 和 Upscale 的 Server 接口，不参与面向用户的对象创建流程。
+
+## 对应文件
+
+```text
+src/anyimage/
+├── operators/debug.py          # 调试请求与结果目录打开
+├── panel.py                    # Debug 面板入口
+└── server/
+    ├── jobs/debug_predictions.py # 四种公开 Debug Job 的共享编排
+    └── outputs/                # 调试产物写出
+```
+
+## 主流程
+
+```mermaid
+flowchart TD
+    Panel["Debug 面板"] --> Operator["选择模型调试 Operator"]
+    Operator --> Request["从 Scene 设置组装请求"]
+    Request --> Job["提交对应 debug Job"]
+    Job --> Output["写出原始预测产物"]
+    Output --> Directory["打开 Job 目录"]
+```
+
+调试入口读取 Scene 中的输入路径、设备与模型参数，直接调用对应 Server Job。任务完成后只打开 Job 目录供检查，不把结果导入为 Blender Image、Mesh 或节点资产。因此它适合验证模型、设备和输出格式，不代表正式功能的用户流程。