feat: 初始化孕育无忧全栈项目基础代码结构

完成项目初始搭建，包含后端FastAPI+MongoDB服务、前端React+Vite项目的完整基础结构，添加各类配置文件与依赖清单，涵盖核心业务初始框架。

backend/app/services/storage.py

@@ -0,0 +1,24 @@
+import os
+import uuid
+from pathlib import Path
+
+import aiofiles
+from fastapi import UploadFile
+
+from app.config import settings
+
+
+async def save_upload_file(file: UploadFile, sub_dir: str = "reports") -> str:
+    """Save uploaded file and return the relative URL path"""
+    upload_path = Path(settings.upload_dir) / sub_dir
+    upload_path.mkdir(parents=True, exist_ok=True)
+
+    ext = Path(file.filename).suffix if file.filename else ".jpg"
+    filename = f"{uuid.uuid4().hex}{ext}"
+    file_path = upload_path / filename
+
+    content = await file.read()
+    async with aiofiles.open(file_path, "wb") as f:
+        await f.write(content)
+
+    return f"/uploads/{sub_dir}/{filename}"