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- Removed outdated logic and ensured all changes are documented and tested for regression.

openspec/changes/refine-image-output-semantics/specs/geometry-depth-controls/spec.md

@@ -0,0 +1,23 @@
+## ADDED Requirements
+
+### Requirement: Geometry depth groups expose Reference Depth
+系统 SHALL 在 `O Image Depth Plane`、`O Image Cutout`、Depth Balloon 与 Depth Surface 的 Geometry Nodes 接口中使用 `Reference Depth` 表示深度纹理的参考距离，并且 MUST 不再公开 `Base Plane Depth`。
+
+#### Scenario: Depth Plane initializes its reference
+- **WHEN** 系统根据 `depth.json` 创建 Depth Plane Modifier
+- **THEN** `reference_depth × uniform_scale` SHALL 写入 `Reference Depth`
+
+#### Scenario: Depth Cutout initializes its reference
+- **WHEN** 系统根据最终网格内容标定 Depth Balloon 或 Depth Surface
+- **THEN** 标定结果 SHALL 写入主 Cutout 与对应子组的 `Reference Depth`
+
+#### Scenario: Node asset exposes the current interface only
+- **WHEN** 系统构建并验证 `O_AnyImage.blend`
+- **THEN** 所有相关节点组、面板、依赖连线和 Modifier 输入 SHALL 只包含 `Reference Depth`，不得保留旧名称或兼容 socket
+
+### Requirement: Reference Depth keeps existing geometry meaning
+`Reference Depth` SHALL 继续作为采样 Depth 的运算基准，不改变 Depth Plane、Depth Balloon 或 Depth Surface 的几何方向、尺度、厚度和位移公式。
+
+#### Scenario: Reference control changes relative depth
+- **WHEN** 用户修改 `Reference Depth`
+- **THEN** Geometry Nodes SHALL 使用 `Reference Depth - sampled depth` 的既有相对深度关系更新几何