🎨 完整的 IOPaint 项目更新

## 主要更新
- ✨ 更新所有依赖到最新稳定版本
- 📝 添加详细的项目文档和模型推荐
- 🔧 配置 VSCode Cloud Studio 预览功能
- 🐛 修复 PyTorch API 弃用警告

## 依赖更新
- diffusers: 0.27.2 → 0.35.2
- gradio: 4.21.0 → 5.46.0
- peft: 0.7.1 → 0.18.0
- Pillow: 9.5.0 → 11.3.0
- fastapi: 0.108.0 → 0.116.2

## 新增文件
- CLAUDE.md - 项目架构和开发指南
- UPGRADE_NOTES.md - 详细的升级说明
- .vscode/preview.yml - 预览配置
- .vscode/LAUNCH_GUIDE.md - 启动指南
- .gitignore - 更新的忽略规则

## 代码修复
- 修复 iopaint/model/ldm.py 中的 torch.cuda.amp.autocast() 弃用警告

## 文档更新
- README.md - 添加模型推荐和使用指南
- 完整的项目源码（iopaint/）
- Web 前端源码（web_app/）

🤖 Generated with Claude Code

iopaint/file_manager/storage_backends.py

@@ -0,0 +1,46 @@
+# Copy from https://github.com/silentsokolov/flask-thumbnails/blob/master/flask_thumbnails/storage_backends.py
+import errno
+import os
+from abc import ABC, abstractmethod
+
+
+class BaseStorageBackend(ABC):
+    def __init__(self, app=None):
+        self.app = app
+
+    @abstractmethod
+    def read(self, filepath, mode="rb", **kwargs):
+        raise NotImplementedError
+
+    @abstractmethod
+    def exists(self, filepath):
+        raise NotImplementedError
+
+    @abstractmethod
+    def save(self, filepath, data):
+        raise NotImplementedError
+
+
+class FilesystemStorageBackend(BaseStorageBackend):
+    def read(self, filepath, mode="rb", **kwargs):
+        with open(filepath, mode) as f:  # pylint: disable=unspecified-encoding
+            return f.read()
+
+    def exists(self, filepath):
+        return os.path.exists(filepath)
+
+    def save(self, filepath, data):
+        directory = os.path.dirname(filepath)
+
+        if not os.path.exists(directory):
+            try:
+                os.makedirs(directory)
+            except OSError as e:
+                if e.errno != errno.EEXIST:
+                    raise
+
+        if not os.path.isdir(directory):
+            raise IOError("{} is not a directory".format(directory))
+
+        with open(filepath, "wb") as f:
+            f.write(data)