feat: 监控告警体系统一重构 + 自动化任务调度引擎 + 监控大屏拆分

告警中心
- 新增统一告警(alert_unified)、监控告警规则(monitor_alert_rule)、指标目录(alert_metric_catalog)
- 通知策略与消息分发(alert_notify_policy/dispatch/message)、静默规则
- 告警引擎按阈值/SNMP 拆分(alert_engine_monitor/snmp)

监控采集
- SNMP 常量/模板与历史指标(snmp templates/constants、snmp_metrics_history、snmp_collect)
- 中间件监控 Redis 采集与种子(middleware_monitor_redis/seed)
- 站点探测 pkg(siteprobe) + 站点视图(site_view)

自动化任务
- cron 调度器(cronscheduler)、脚本运行器(scriptrunner)、系统任务(systask)及运行记录(cron_job_run、system_task)

审计与凭证
- 审计设置(audit_setting) + 历史清理(auditcleaner)

前端
- 监控页面(host/middleware/site/snmp)拆分为子模块并大屏化
- 告警中心多 Tab(规则/指标目录/通知策略/静默)、任务管理组件重构、Agent CLI Markdown 渲染
- 移除旧脚本卡片/详情/日志组件，统一为 ScriptTable/ScriptCodeEditor/TerminalOutput

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

backend/controller/audit_setting.go

@@ -0,0 +1,121 @@
+package controller
+
+import (
+	"fmt"
+	"net/http"
+	"time"
+
+	"ezops/model"
+	"ezops/pkg/auditcleaner"
+
+	"github.com/gin-gonic/gin"
+	"gorm.io/gorm"
+)
+
+// AuditSettingsHandler 审计策略配置 // Logan.Li
+type AuditSettingsHandler struct {
+	db *gorm.DB
+}
+
+func NewAuditSettingsHandler(db *gorm.DB) *AuditSettingsHandler {
+	return &AuditSettingsHandler{db: db}
+}
+
+func (h *AuditSettingsHandler) getOrCreate() (model.AuditSettings, error) {
+	var s model.AuditSettings
+	err := h.db.First(&s).Error
+	if err == nil {
+		return s, nil
+	}
+	if err != gorm.ErrRecordNotFound {
+		return s, err
+	}
+	s = model.AuditSettings{RetentionDays: 180, RecordAll: true}
+	return s, h.db.Create(&s).Error
+}
+
+// GetAuditSettings 获取审计策略 // Logan.Li
+// GET /api/v1/admin/audit-settings
+func (h *AuditSettingsHandler) GetAuditSettings(c *gin.Context) {
+	s, err := h.getOrCreate()
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, model.Response{Code: 500, Message: "读取配置失败"})
+		return
+	}
+	c.JSON(http.StatusOK, model.Response{
+		Code:    200,
+		Message: "success",
+		Data: gin.H{
+			"retention_days":       s.RetentionDays,
+			"record_all":             s.RecordAll,
+			"last_cleanup_at":        s.LastCleanupAt,
+			"last_cleanup_summary":   s.LastCleanupSummary,
+			"allowed_retention_days": model.AllowedAuditRetentionDays,
+		},
+	})
+}
+
+// ApplyAuditSettings 应用审计策略并立即清理超期日志 // Logan.Li
+// PUT /api/v1/admin/audit-settings
+func (h *AuditSettingsHandler) ApplyAuditSettings(c *gin.Context) {
+	var req struct {
+		RetentionDays int  `json:"retention_days" binding:"required"`
+		RecordAll     bool `json:"record_all"`
+	}
+	if err := c.ShouldBindJSON(&req); err != nil {
+		c.JSON(http.StatusBadRequest, model.Response{Code: 400, Message: "请求参数错误"})
+		return
+	}
+	if !model.IsValidRetentionDays(req.RetentionDays) {
+		c.JSON(http.StatusBadRequest, model.Response{
+			Code:    400,
+			Message: "保留天数仅支持 7 / 15 / 30 / 90 / 180 / 365",
+		})
+		return
+	}
+
+	s, err := h.getOrCreate()
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, model.Response{Code: 500, Message: "读取配置失败"})
+		return
+	}
+
+	s.RetentionDays = req.RetentionDays
+	s.RecordAll = req.RecordAll
+
+	cleanResult, cleanErr := auditcleaner.Run(h.db, req.RetentionDays)
+	now := time.Now()
+	s.LastCleanupAt = &now
+	s.LastCleanupSummary = cleanResult.SummaryJSON()
+
+	if err := h.db.Save(&s).Error; err != nil {
+		c.JSON(http.StatusInternalServerError, model.Response{Code: 500, Message: "保存配置失败"})
+		return
+	}
+
+	msg := fmt.Sprintf("已应用保留 %d 天策略", req.RetentionDays)
+	if cleanErr != nil {
+		c.JSON(http.StatusInternalServerError, model.Response{
+			Code:    500,
+			Message: "配置已保存，但立即清理失败: " + cleanErr.Error(),
+		})
+		return
+	}
+	if cleanResult.Total > 0 {
+		msg += fmt.Sprintf("，已清理 %d 条超期记录", cleanResult.Total)
+	} else {
+		msg += "，暂无超期记录需清理"
+	}
+
+	c.JSON(http.StatusOK, model.Response{
+		Code:    200,
+		Message: msg,
+		Data: gin.H{
+			"retention_days":     s.RetentionDays,
+			"record_all":         s.RecordAll,
+			"last_cleanup_at":    s.LastCleanupAt,
+			"last_cleanup_summary": s.LastCleanupSummary,
+			"cleanup":            cleanResult,
+		},
+	})
+}