Add comprehensive documentation for SnapForm extension

- Created development.md for development setup and licensing information.
- Added features.md detailing functionalities and usage instructions for developers and users.
- Introduced index.md to serve as a navigation hub for the documentation.
- Developed outputs.md to explain output formats and their specifications.
- Established service.md to describe the AI Service architecture and environment setup.
- Created surface.md to outline the process of converting Image Empty to perspective meshes.

docs/development.md

@@ -0,0 +1,42 @@
+# 开发与许可证
+
+## 开发
+
+```bash
+uv run python prepare_vendor.py
+uv run pytest tests -v
+uv run python pack.py
+```
+
+项目结构：
+
+```text
+.
+├── vendor.lock.toml        第三方构建输入的版本、URL 与 SHA-256
+├── prepare_vendor.py       下载并校验第三方构建输入
+├── pack.py
+├── patches/                进入 Git 的 DA3 源码覆盖文件
+├── vendor/                 不进入 Git 的下载缓存；本地调试也直接读取这里
+├── src/
+│   └── snapform/
+│       ├── blender_manifest.toml
+│       ├── service.py
+│       ├── install_env.py
+│       ├── models.py
+│       ├── image_depth.py
+│       ├── operators.py
+│       ├── panel.py
+│       ├── preferences.py
+│       ├── properties.py
+│       ├── client.py
+│       └── worker.py
+└── tests/
+```
+
+## 上游与许可证
+
+- Depth Anything 3 代码采用 Apache 2.0。
+- BEN2 代码与模型权重采用 MIT License。
+- 本 Extension 代码采用 GPL-3.0-or-later。
+- 模型权重许可证由所选 Hugging Face 模型仓库决定，Extension 下载前会在界面显示。
+