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/main.py

@@ -0,0 +1,99 @@
+"""FastAPI 应用入口：lifespan 管理 scheduler、首次启动创建 admin。"""
+import logging
+from contextlib import asynccontextmanager
+
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+from fastapi.responses import JSONResponse
+from sqlalchemy.exc import OperationalError
+
+from app.api.router import api_router
+from app.config import get_settings
+from app.database import Base, SessionLocal, engine
+from app.models.user import User
+from app.scheduler.scheduler import scheduler_lifespan
+from app.security import hash_password
+from app.utils.logging import setup_logging
+
+setup_logging()
+log = logging.getLogger(__name__)
+settings = get_settings()
+
+
+def init_database() -> None:
+    """建表（Alembic 是首选；这里兜底确保首次启动也能跑）。"""
+    try:
+        # 实际生产用 alembic upgrade head；这里仅当表不存在时创建
+        Base.metadata.create_all(bind=engine)
+        log.info("Database tables ensured")
+    except OperationalError as e:
+        log.error("Database init failed: %s", e)
+        raise
+
+
+def init_admin() -> None:
+    """首次启动创建 admin 账号（仅当 users 表为空时）。"""
+    with SessionLocal() as db:
+        try:
+            existing = db.query(User).count()
+            if existing > 0:
+                log.info("Existing users found (%d), skip admin init", existing)
+                return
+            admin = User(
+                username="admin",
+                password_hash=hash_password(settings.INITIAL_ADMIN_PASSWORD),
+                is_admin=True,
+                is_active=True,
+            )
+            db.add(admin)
+            db.commit()
+            log.warning(
+                "Initial admin account created. username=admin  "
+                "Please change the password after first login."
+            )
+        except Exception:
+            db.rollback()
+            raise
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    init_database()
+    init_admin()
+    async with scheduler_lifespan():
+        log.info("Application ready")
+        yield
+    log.info("Application shutting down")
+
+
+app = FastAPI(
+    title="Backup System",
+    description="数据备份管理系统 - MySQL / 目录 备份到本地 / S3",
+    version="0.1.0",
+    lifespan=lifespan,
+)
+
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=settings.cors_origins_list,
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+
+@app.get("/api/health")
+def health() -> dict:
+    return {"status": "ok"}
+
+
+app.include_router(api_router, prefix="/api")
+
+
+@app.exception_handler(Exception)
+async def global_exception_handler(request, exc):
+    log.exception("Unhandled error on %s %s", request.method, request.url)
+    return JSONResponse(
+        status_code=500,
+        content={"detail": f"Internal server error: {type(exc).__name__}"},
+    )