feat: ETCD 备份 + 邮件/飞书通知

ETCD 备份（新增类型）：
- 后端 core/backup/etcd.py：调用 etcdctl snapshot save（v3.5.17 二进制）
  生成快照文件，与 META.txt 一起 tar.gz 流式打包上传。
- 配置支持 endpoints（逗号分隔多节点）、basic auth、TLS（cacert/cert/key）。
- Dockerfile 下载 etcdctl 二进制（绕过 apt 签名问题）。

通知模块：
- 核心 app/core/notify.py：
  - 邮件：smtplib + MIMEMultipart（线程池里跑避免阻塞）
  - 飞书：httpx 调自定义机器人 webhook，发 interactive card
- settings API：
  - GET/PUT /api/settings/notifications（密码脱敏 *** 编辑占位）
  - POST /api/settings/notifications/test 测试通道
- Job 增加 notify_on 字段（none/failure/all），Alembic 0002 迁移。
- executor 在 run 完成后根据 job.notify_on 与 run.status 异步触发通知，
  重新加载最新 run 信息生成上下文。

前端：
- JobForm 加 ETCD 表单字段与 notify_on 选择器；type 选项加 etcd。
- JobList 显示通知策略徽标。
- Settings 页加通知配置卡片：邮件（折叠面板 + 测试按钮）+ 飞书 + 保存。
- 新增 api/settings.ts。
- 类型扩展：EtcdSourceConfig、NotificationsConfig、SmtpConfig。

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

backend/app/core/executor.py

@@ -14,6 +14,7 @@ from sqlalchemy.orm import Session
 
 from app.core.backup.base import BaseBackup
 from app.core.backup.directory import DirectoryBackup
+from app.core.backup.etcd import EtcdBackup
 from app.core.backup.influxdb import InfluxDBBackup
 from app.core.backup.mysql import MySQLBackup
 from app.core.retention import apply_retention
@@ -35,6 +36,8 @@ def _make_backup(job: Job) -> BaseBackup:
         return DirectoryBackup(src, job.name)
     if job.type == "influxdb":
         return InfluxDBBackup(src, job.name)
+    if job.type == "etcd":
+        return EtcdBackup(src, job.name)
     raise ValueError(f"Unsupported job type: {job.type}")
 
 
@@ -127,6 +130,63 @@ async def run_backup(run_id: int, trigger: str = "manual") -> None:
             db.add(run_log)
             db.commit()
             log.info("Backup run_id=%s finished status=%s", run_id, run.status)
+
+        # 触发通知（在事务外，避免阻塞 executor；fire and forget）
+        try:
+            should_notify = (
+                job.notify_on == "all"
+                or (job.notify_on == "failure" and run.status == "failed")
+            )
+            if should_notify:
+                asyncio.create_task(_dispatch_notification(job.id, run.id))
+        except Exception as e:
+            log.warning("Failed to schedule notification: %s", e)
+    finally:
+        db.close()
+
+
+async def _dispatch_notification(job_id: int, run_id: int) -> None:
+    """从 DB 重新加载最新 run 状态后发通知。"""
+    from app.core.notify import NotificationContext, send_notifications
+    from app.models.setting import Setting
+    from app.utils.crypto import decrypt_dict
+
+    db = SessionLocal()
+    try:
+        job = db.get(Job, job_id)
+        run = db.get(Run, run_id)
+        if not job or not run:
+            return
+
+        notify_row = db.get(Setting, "notifications")
+        if not notify_row or not notify_row.value:
+            return
+        try:
+            settings = decrypt_dict(notify_row.value)
+        except Exception:
+            return
+
+        if not (settings.get("email_enabled") or settings.get("feishu_enabled")):
+            return
+
+        ctx = NotificationContext(
+            job_name=job.name,
+            job_type=job.type,
+            status=run.status,
+            run_id=run.id,
+            artifact_size=run.artifact_size,
+            duration_seconds=run.duration_seconds,
+            error_message=run.error_message,
+            artifact_path=run.artifact_path,
+            started_at=run.started_at.isoformat() if run.started_at else None,
+            finished_at=run.finished_at.isoformat() if run.finished_at else None,
+        )
+
+        result = await send_notifications(settings, ctx)
+        log.info(
+            "Notification dispatched for run_id=%s: email_ok=%s feishu_ok=%s",
+            run.id, result.email_ok, result.feishu_ok,
+        )
     finally:
         db.close()