Refactor Cutout and Image Editing Logic

- Renamed "Base Plane Depth" to "Reference Depth" across validate_cutout.py for consistency.
- Introduced a new specification for Cutout mesh sampling to ensure source pixel spacing is preserved and limits are applied correctly.
- Unified naming conventions for image editing results to maintain consistency across Remove Background, Upscale, and Crop operations.
- Updated the handling of Refine Selection to ensure it retains the original bounds and does not apply unnecessary cropping.
- Enhanced material generation logic to connect image color directly to IOR Level, improving the rendering of dark areas.
- Established clear requirements for geometry depth controls and image result materials to ensure consistent behavior across different components.
- Removed outdated logic and ensured all changes are documented and tested for regression.

docs/internals/runtime.md

@@ -48,13 +48,13 @@ Job 在阶段边界调用 `context.check_cancelled()`，并把稳定产物写入
 | `generate-cutout-artifacts` | 按需执行 Refine Selection，并生成 Depth 或 Normal 文件产物 |
 | `debug-*` | 保存模型适配层的直接输出 |
 
-`generate-depth-plane-geometry` 对应 `jobs/depth_plane.py`；`generate-cutout-artifacts` 对应 `jobs/cutout.py`。共享的 MoGe-2 推理编排位于 `geometry/prediction_artifacts.py`，它把最终 Selection RGBA 合成到黑底后执行推理，并把单帧 `GeometryFrame` 交给 Depth、Normal 与 Metadata Writer。Depth EXR 与元数据写入位于 `geometry/depth_texture.py`，Normal 编码位于 `geometry/normal_texture.py`，Refine Selection 的通用实现位于 `selection/refine_selection.py`。
+`generate-depth-plane-geometry` 对应 `jobs/depth_plane.py`；`generate-cutout-artifacts` 对应 `jobs/cutout.py`。共享的 MoGe-2 推理编排位于 `geometry/prediction_artifacts.py`，它把最终 Selection RGBA 合成到黑底后执行推理，并把单帧 `GeometryFrame` 交给 Depth、Normal 与 Metadata Writer。Depth EXR 与元数据写入位于 `geometry/depth_texture.py`，Normal 编码位于 `geometry/normal_texture.py`。`selection/refine_selection.py` 使用 BEN2 生成与输入同尺寸的 `Source Alpha × BEN2 Alpha` RGBA；Selection Mask 由 Blender 在最终图片或网格阶段组合。
 
 ## 尺寸约束
 
 `server/media/resolution.py` 提供 **Maximum AI Input Size**，默认 `2048 px`。它限制 Upscale 的可提交源图长边，以及 Depth、Normal Map、Refine Selection 的模型分析图长边；材质颜色图使用原始分辨率。
 
-Blender 侧的 **Maximum Cutout Mesh Resolution** 统一限制所有 Cutout Shape 的网格采样密度。
+Blender 侧的 **Maximum Cutout Mesh Resolution** 统一限制所有 Cutout Shape 实际几何范围的最长网格采样边，不限制 Selection bounds 的原始像素尺寸。
 
 `generate-depth-plane-geometry` 与 `generate-cutout-artifacts` 只接受一帧，因此 Depth Plane 与 Cutout 是静态图工作流。Remove Background 与 Upscale 继续通过媒体入口处理单图、视频和序列帧。