feat(运维监控): 增强监控功能和健康评分系统

后端改进：
- 新增健康评分计算服务（ops_health_score.go）
- 添加分布式锁支持（ops_advisory_lock.go）
- 优化指标采集和聚合逻辑
- 新增运维指标采集间隔配置（60-3600秒）
- 移除未使用的WebSocket查询token认证中间件
- 改进清理服务和告警评估逻辑

前端改进：
- 简化OpsDashboard组件结构
- 完善国际化文本（中英文）
- 新增运维监控相关API类型定义
- 添加运维指标采集间隔设置界面
- 优化错误详情模态框

测试：
- 添加健康评分单元测试
- 更新API契约测试

backend/internal/service/ops_cleanup_service.go

@@ -300,30 +300,36 @@ func (s *OpsCleanupService) tryAcquireLeaderLock(ctx context.Context) (func(), b
 		return nil, true
 	}
 
-	if s.redisClient == nil {
-		s.warnNoRedisOnce.Do(func() {
-			log.Printf("[OpsCleanup] redis not configured; running without distributed lock")
-		})
-		return nil, true
-	}
-
 	key := opsCleanupLeaderLockKeyDefault
 	ttl := opsCleanupLeaderLockTTLDefault
 
-	ok, err := s.redisClient.SetNX(ctx, key, s.instanceID, ttl).Result()
-	if err != nil {
+	// Prefer Redis leader lock when available, but avoid stampeding the DB when Redis is flaky by
+	// falling back to a DB advisory lock.
+	if s.redisClient != nil {
+		ok, err := s.redisClient.SetNX(ctx, key, s.instanceID, ttl).Result()
+		if err == nil {
+			if !ok {
+				return nil, false
+			}
+			return func() {
+				_, _ = opsCleanupReleaseScript.Run(ctx, s.redisClient, []string{key}, s.instanceID).Result()
+			}, true
+		}
+		// Redis error: fall back to DB advisory lock.
 		s.warnNoRedisOnce.Do(func() {
-			log.Printf("[OpsCleanup] leader lock SetNX failed; running without lock: %v", err)
+			log.Printf("[OpsCleanup] leader lock SetNX failed; falling back to DB advisory lock: %v", err)
+		})
+	} else {
+		s.warnNoRedisOnce.Do(func() {
+			log.Printf("[OpsCleanup] redis not configured; using DB advisory lock")
 		})
-		return nil, true
 	}
+
+	release, ok := tryAcquireDBAdvisoryLock(ctx, s.db, hashAdvisoryLockID(key))
 	if !ok {
 		return nil, false
 	}
-
-	return func() {
-		_, _ = opsCleanupReleaseScript.Run(ctx, s.redisClient, []string{key}, s.instanceID).Result()
-	}, true
+	return release, true
 }
 
 func (s *OpsCleanupService) recordHeartbeatSuccess(runAt time.Time, duration time.Duration) {