Add comprehensive tests for image processing and mask functionalities

- Introduced tests for color image handling, ensuring source preservation and premultiplied alpha usage.
- Implemented tests for brush stroke operations, validating segment boundaries and brush anti-aliasing.
- Added tests for frame anti-aliasing, confirming correct rendering behavior with various alpha values and depth settings.
- Created tests for frame projection, ensuring accurate overlap calculations and half-plane clipping.
- Developed tests for image premultiplied retention, verifying behavior during loading and packing processes.
- Added undo functionality tests for mask operations, ensuring single transaction behavior during edits.

docs/getting-started/installation.md

@@ -27,7 +27,7 @@ macOS arm64 提供 **CPU** 与 **CoreML**。CoreML 由系统在 Apple CPU、GPU
 Environment 检测后显示 Diagnostics。Depth & Normal、Remove Background、Upscale 与 Cutout 是默认展开的可折叠功能区，各自包含对应设置和模型状态。其中：
 
 - **Default Upscale Model**：Upscale 使用的模型，默认是 General WDN x4v3。
-- **Maximum AI Input Size**：Upscale、Depth、Normal Map 与 Refine Selection 的 AI 输入长边上限，默认 2048 px；颜色贴图保留原始分辨率。
+- **Maximum AI Input Size**：Upscale、Depth 与 Normal Map 的 AI 输入长边上限，默认 2048 px；颜色贴图保留原始分辨率。
 - **Maximum Cutout Mesh Resolution**：所有 Cutout Shape 的网格采样长边上限，默认 1024，独立于 AI 输入尺寸。
 
 Depth & Normal 提供三档 MoGe-2，Depth Plane 与 Cutout Depth / Normal Map 共用当前选择。可选模型的 **Ready** 状态或 **Download** 按钮位于选择项下方；Cutout 区提供独立网格上限与 Balloon Profile。