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/upscale.md

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+# Upscale
+
+本页对应 `src/anyimage/operators/upscale.py`。该模块读取扩展首选项中的模型与全局 AI 输入长边上限，提交 4× 高清任务，并维护高清结果到原始 Image 的引用。
+
+## 对应文件
+
+```text
+src/anyimage/
+├── operators/
+│   ├── upscale.py                 # Blender 入口、任务参数与结果替换
+│   └── common/image.py            # 媒体输入准备与结果 Image 创建
+└── server/
+    ├── jobs/upscale.py            # 单图与多帧任务编排
+    ├── media/resolution.py        # 共用长边限制与等比缩放
+    ├── models/upscale.py          # 输入约束与 Alpha 合并
+    └── models/onnx_upscale.py     # 分块 4× ONNX 推理
+```
+
+## 主流程
+
+```mermaid
+flowchart TD
+    Empty["Image Empty"] --> Source["解析原始 Image"]
+    Source --> Prepare["准备媒体输入"]
+    Prepare --> Job["upscale-image Job"]
+    Job --> Limit["按全局输入长边上限等比缩放"]
+    Limit --> RGB["分块执行 4× RGB 推理"]
+    Limit --> Alpha["独立缩放 Alpha"]
+    RGB --> Merge["合并 RGBA 结果"]
+    Alpha --> Merge
+    Merge --> Replace["导入并替换当前 Image"]
+```
+
+模型以 256×256 分块处理 RGB，并带入相邻上下文以减弱块边界；Alpha 按同一受限输入尺寸单独缩放，最后合并为 RGBA。`max_input_size` 来自全局 **Maximum AI Input Size**，默认 `2048`，只约束送入模型的长边；4× 输出长边因此默认为最多 `8192`。输入尺寸不超过上限时不会发生预缩放。
+
+结果以 `_upscale.png` 结尾，并通过 `Image.anyimage_upscale_source` 保存原图引用。再次对高清结果执行时，Operator 会从原图重新生成，而不是继续放大上一次输出。模型与全局输入上限在每次执行时从 Preferences 读取，再写入可序列化的隐藏属性交给 Job。Provider 资源错误会释放当前 Upscale Session，并提示降低全局输入上限或改用 CPU。