feat: Implement upscale functionality with ONNX models

- Added upscale operator to handle image upscaling by 4x using AI models.
- Introduced new jobs for upscale processing in the server, including debug and standard upscale jobs.
- Created a new ONNX model handler for upscale operations, supporting tiled inference and resource management.
- Updated tests to cover new upscale functionality, including input validation and output verification.
- Added documentation for the upscale feature, detailing usage and model options.

AGENTS.md

@@ -69,6 +69,7 @@ uv lock --refresh
 - 只为特殊、非常规或存在兼容性原因的实现写注释，不复述代码本身
 - 删除功能时同时删除无效参数、分支、测试和文档，不保留没有实际消费者的兼容层
 - Blender 侧不载入 AI 依赖：UI、Operator 和结果导入放在 `src/anyimage/` 或 `src/anyimage/blender/`，模型下载、ONNX 推理和输出放在 `src/anyimage/server/`
+- 扩展级设置及其读取入口统一放在 `preferences.py`；使用 `addon_preferences()` 读取，不把 Blender Add-on Preferences 的定位、默认值或路径解析放进专门管理 BlendJob 的 `runtime.py`
 - Job 参数使用可序列化的普通字典；Blender 数据只能在主线程的 Operator 响应阶段读写
 - 新增或修改 Blender 类型时同步检查 `src/anyimage/__init__.py` 的注册与逆序注销，并补充对应测试
 - 依赖版本、wheel 或 Manifest 改变时同步检查 `pyproject.toml`、`uv.lock`、`blender_manifest.toml` 和打包测试