feat: 数据备份管理系统 v0.1.0

带 Web 操作界面的备份系统，支持：
- 数据源：MySQL 数据库（mysqldump）、服务器目录（tar.gz）
- 存储目标：本地目录、S3 兼容对象存储（MinIO/Ceph/AWS S3）
- 触发方式：手动 + Cron 定时调度（APScheduler）
- 备份还原：MySQL 库、目录
- JWT 登录认证 + Fernet 字段加密
- 保留策略：按数量 + 按天数双重清理

技术栈：FastAPI + SQLAlchemy 2 + APScheduler + aioboto3；
前端 Vite + React 18 + TypeScript + Ant Design 5 + Zustand。
Docker Compose 一键起。

Co-Authored-By: Claude <noreply@anthropic.com>

backend/app/core/storage/local.py

@@ -0,0 +1,98 @@
+"""本地文件系统存储。"""
+import asyncio
+import hashlib
+import os
+import shutil
+from datetime import datetime
+from pathlib import Path
+from typing import AsyncIterator
+
+import aiofiles
+
+from app.core.storage.base import BaseStorage, StorageObject
+from app.utils.logging import get_logger
+
+log = get_logger(__name__)
+
+
+class LocalStorage(BaseStorage):
+    type = "local"
+
+    def __init__(self, config: dict):
+        super().__init__(config)
+        self.root: str = os.path.abspath(config["path"])
+        Path(self.root).mkdir(parents=True, exist_ok=True)
+
+    def _resolve(self, key: str) -> Path:
+        # 防 path traversal：禁止 ..
+        if ".." in key.split("/"):
+            raise ValueError(f"Invalid key (path traversal): {key}")
+        return Path(self.root) / key
+
+    async def test_connection(self) -> tuple[bool, str]:
+        try:
+            Path(self.root).mkdir(parents=True, exist_ok=True)
+            test_file = Path(self.root) / ".backup_system_test"
+            async with aiofiles.open(test_file, "w") as f:
+                await f.write("ok")
+            # aiofiles 不暴露 os 命名空间，用线程池跑同步删除
+            await asyncio.to_thread(os.remove, test_file)
+            return True, f"OK: writable {self.root}"
+        except Exception as e:
+            return False, f"FAIL: {e}"
+
+    async def upload_stream(
+        self,
+        source: AsyncIterator[bytes],
+        key: str,
+        content_type: str = "application/octet-stream",
+    ) -> tuple[int, str]:
+        path = self._resolve(key)
+        path.parent.mkdir(parents=True, exist_ok=True)
+        sha = hashlib.sha256()
+        size = 0
+        async with aiofiles.open(path, "wb") as f:
+            async for chunk in source:
+                await f.write(chunk)
+                sha.update(chunk)
+                size += len(chunk)
+        return size, sha.hexdigest()
+
+    async def download_stream(self, key: str) -> AsyncIterator[bytes]:
+        path = self._resolve(key)
+        if not path.exists():
+            raise FileNotFoundError(f"Not found: {key}")
+        async with aiofiles.open(path, "rb") as f:
+            while True:
+                chunk = await f.read(64 * 1024)
+                if not chunk:
+                    break
+                yield chunk
+
+    async def delete(self, key: str) -> None:
+        path = self._resolve(key)
+        try:
+            path.unlink()
+        except FileNotFoundError:
+            pass
+
+    async def exists(self, key: str) -> bool:
+        return self._resolve(key).exists()
+
+    async def list(self, prefix: str = "") -> list[StorageObject]:
+        base = Path(self.root) / prefix if prefix else Path(self.root)
+        if not base.exists():
+            return []
+        out: list[StorageObject] = []
+        for p in base.rglob("*"):
+            if p.is_file():
+                rel = p.relative_to(Path(self.root)).as_posix()
+                st = p.stat()
+                out.append(
+                    StorageObject(
+                        key=rel,
+                        size=st.st_size,
+                        last_modified=datetime.fromtimestamp(st.st_mtime).isoformat(),
+                    )
+                )
+        return out