feat: 添加通知与告警模块

- 通知渠道支持配置多个 SMTP 账号，配置整体加密落库，删除时清理规则与事件设置中的引用
- 告警规则支持 18 种指标：CPU/内存/Swap/负载/磁盘用量与 inode/磁盘与网卡速率/网站 5xx 与错误率、
  服务与项目与容器与应用与数据库运行状态、证书与网站剩余天数，可配连续命中次数与静默期
- 系统事件通知覆盖证书续签失败、备份失败、后台任务失败、计划任务失败、网站到期、防篡改拦截、
  面板健康问题、面板登录与爆破、SSH 登录与爆破
- 计划任务统一经 wrapper 执行以捕获退出码，flock 抢锁失败不计为失败
- 监控页改造为系统/告警/设置三 Tab
- 数据库驱动建连打通 context 并补齐连接超时，探测不再阻塞告警评估

close #1041

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

internal/command/command.go

@@ -21,7 +21,7 @@ var Package = do.Package(
 	do.LazyNamed(Prefix+"bind-ip", BindIPCommand), do.LazyNamed(Prefix+"bind-ua", BindUACommand),
 	do.LazyNamed(Prefix+"website", WebsiteCommand), do.LazyNamed(Prefix+"database", DatabaseCommand),
 	do.LazyNamed(Prefix+"backup", BackupCommand), do.LazyNamed(Prefix+"restore", RestoreCommand),
-	do.LazyNamed(Prefix+"cutoff", CutoffCommand),
+	do.LazyNamed(Prefix+"cutoff", CutoffCommand), do.LazyNamed(Prefix+"cron", CronCommand),
 	do.LazyNamed(Prefix+"app", AppCommand), do.LazyNamed(Prefix+"setting", SettingCommand),
 )
 

internal/command/cron.go

@@ -0,0 +1,42 @@
+package command
+
+import (
+	"context"
+
+	"github.com/leonelquinteros/gotext"
+	"github.com/samber/do/v2"
+	"github.com/urfave/cli/v3"
+
+	"github.com/acepanel/panel/v3/internal/service"
+)
+
+// CronCommand 计划任务命令组
+func CronCommand(i do.Injector) (*cli.Command, error) {
+	t := do.MustInvoke[*gotext.Locale](i)
+	return &cli.Command{
+		Name:  "cron",
+		Usage: t.Get("Cron task"),
+		Commands: []*cli.Command{
+			{
+				Name:  "failed",
+				Usage: t.Get("Report a failed cron task, called by the task wrapper script"),
+				Flags: []cli.Flag{
+					&cli.UintFlag{
+						Name:     "id",
+						Aliases:  []string{"i"},
+						Usage:    t.Get("Cron task ID"),
+						Required: true,
+					},
+					&cli.IntFlag{
+						Name:    "code",
+						Aliases: []string{"c"},
+						Usage:   t.Get("Exit code"),
+					},
+				},
+				Action: func(ctx context.Context, cmd *cli.Command) error {
+					return do.MustInvoke[*service.CliService](i).CronFailed(ctx, cmd)
+				},
+			},
+		},
+	}, nil
+}