feat(ops): 添加高级设置API支持

- 新增OpsAdvancedSettings数据模型
- 支持数据保留策略配置（错误日志、分钟级指标、小时级指标）
- 支持数据聚合开关配置
- 添加GET/PUT /admin/ops/advanced-settings接口
- 添加配置校验和默认值处理

相关文件：
- backend/internal/service/ops_settings_models.go
- backend/internal/service/ops_settings.go
- backend/internal/handler/admin/ops_settings_handler.go
- backend/internal/server/routes/admin.go
- backend/internal/service/domain_constants.go

backend/internal/service/ops_settings_models.go

@@ -68,3 +68,21 @@ type OpsAlertRuntimeSettings struct {
 	Silencing       OpsAlertSilencingSettings  `json:"silencing"`
 }
 
+// OpsAdvancedSettings stores advanced ops configuration (data retention, aggregation).
+type OpsAdvancedSettings struct {
+	DataRetention OpsDataRetentionSettings `json:"data_retention"`
+	Aggregation   OpsAggregationSettings   `json:"aggregation"`
+}
+
+type OpsDataRetentionSettings struct {
+	CleanupEnabled            bool   `json:"cleanup_enabled"`
+	CleanupSchedule           string `json:"cleanup_schedule"`
+	ErrorLogRetentionDays     int    `json:"error_log_retention_days"`
+	MinuteMetricsRetentionDays int   `json:"minute_metrics_retention_days"`
+	HourlyMetricsRetentionDays int   `json:"hourly_metrics_retention_days"`
+}
+
+type OpsAggregationSettings struct {
+	AggregationEnabled bool `json:"aggregation_enabled"`
+}
+