fix: Redis集群查询+metrics修复 — 单节点连接替代ClusterClient

- crypto.go: decryptPassword 自动处理 enc: 前缀，避免调用方遗漏
- redis.go: getRedisClient 统一使用 redis.NewClient 单节点连接
  ClusterClient 拓扑发现(CLUSTER SLOTS)在Docker内网IP不可达时超时
  redisClientWrapper 全部方法改为使用 Client (不再走 ClusterClient)
  ScanAllKeys 简化为单节点 SCAN
- connection_tester.go: getRedisMetrics 统一单节点连接采集metrics
  删除 isCluster 分支的 ClusterClient 代码，避免5秒超时

backend/internal/handler/redis.go

@@ -21,221 +21,127 @@ type redisClientWrapper struct {
 }
 
 func (w *redisClientWrapper) Close() {
-	if w.isCluster {
-		w.ClusterClient.Close()
-	} else {
+	// Always close the single-node Client (cluster uses single-node now)
+	if w.Client != nil {
 		w.Client.Close()
 	}
+	if w.ClusterClient != nil {
+		w.ClusterClient.Close()
+	}
 }
 
 // Ping, Info, DBSize, Scan, Type, TTL, Get, LRange, SMembers, ZRangeWithScores, HGetAll,
 // SlowLogGet, ClientList, Do, Set, RPush, SAdd, HSet, Expire, Del — unified interface via wrapper methods
+// NOTE: All methods use Client (single-node). isCluster flag is only for ScanAllKeys behavior.
 
 func (w *redisClientWrapper) Ping(ctx context.Context) *redis.StatusCmd {
-	if w.isCluster {
-		return w.ClusterClient.Ping(ctx)
-	}
 	return w.Client.Ping(ctx)
 }
 
 func (w *redisClientWrapper) Info(ctx context.Context, sections ...string) *redis.StringCmd {
-	if w.isCluster {
-		return w.ClusterClient.Info(ctx, sections...)
-	}
 	return w.Client.Info(ctx, sections...)
 }
 
 func (w *redisClientWrapper) DBSize(ctx context.Context) *redis.IntCmd {
-	if w.isCluster {
-		return w.ClusterClient.DBSize(ctx)
-	}
 	return w.Client.DBSize(ctx)
 }
 
 func (w *redisClientWrapper) Scan(ctx context.Context, cursor uint64, match string, count int64) *redis.ScanCmd {
-	if w.isCluster {
-		return w.ClusterClient.Scan(ctx, cursor, match, count)
-	}
 	return w.Client.Scan(ctx, cursor, match, count)
 }
 
-// ScanAllKeys scans keys across ALL master nodes in cluster mode, or single node in standalone.
-// Returns merged deduplicated keys.
+// ScanAllKeys scans keys on the connected node.
+// For clusters, this only scans keys on the single connected node (not all masters).
 func (w *redisClientWrapper) ScanAllKeys(ctx context.Context, match string, count int) ([]string, error) {
-	if !w.isCluster {
-		// Standalone: iterate SCAN until cursor returns to 0
-		var allKeys []string
-		cursor := uint64(0)
-		for {
-			keys, nextCursor, err := w.Client.Scan(ctx, cursor, match, int64(count)).Result()
-			if err != nil {
-				return allKeys, err
-			}
-			allKeys = append(allKeys, keys...)
-			cursor = nextCursor
-			if cursor == 0 {
-				break
-			}
-		}
-		return allKeys, nil
-	}
-
-	// Cluster: iterate SCAN on every master node
 	var allKeys []string
-	seen := make(map[string]bool)
-	err := w.ClusterClient.ForEachMaster(ctx, func(ctx context.Context, node *redis.Client) error {
-		cursor := uint64(0)
-		for {
-			keys, nextCursor, err := node.Scan(ctx, cursor, match, int64(count)).Result()
-			if err != nil {
-				return err
-			}
-			for _, k := range keys {
-				if !seen[k] {
-					seen[k] = true
-					allKeys = append(allKeys, k)
-				}
-			}
-			cursor = nextCursor
-			if cursor == 0 {
-				break
-			}
+	cursor := uint64(0)
+	for {
+		keys, nextCursor, err := w.Client.Scan(ctx, cursor, match, int64(count)).Result()
+		if err != nil {
+			return allKeys, err
 		}
-		return nil
-	})
-	return allKeys, err
+		allKeys = append(allKeys, keys...)
+		cursor = nextCursor
+		if cursor == 0 {
+			break
+		}
+	}
+	return allKeys, nil
 }
 
 func (w *redisClientWrapper) Type(ctx context.Context, key string) *redis.StatusCmd {
-	if w.isCluster {
-		return w.ClusterClient.Type(ctx, key)
-	}
 	return w.Client.Type(ctx, key)
 }
 
 func (w *redisClientWrapper) TTL(ctx context.Context, key string) *redis.DurationCmd {
-	if w.isCluster {
-		return w.ClusterClient.TTL(ctx, key)
-	}
 	return w.Client.TTL(ctx, key)
 }
 
 func (w *redisClientWrapper) Get(ctx context.Context, key string) *redis.StringCmd {
-	if w.isCluster {
-		return w.ClusterClient.Get(ctx, key)
-	}
 	return w.Client.Get(ctx, key)
 }
 
 func (w *redisClientWrapper) LRange(ctx context.Context, key string, start, stop int64) *redis.StringSliceCmd {
-	if w.isCluster {
-		return w.ClusterClient.LRange(ctx, key, start, stop)
-	}
 	return w.Client.LRange(ctx, key, start, stop)
 }
 
 func (w *redisClientWrapper) SMembers(ctx context.Context, key string) *redis.StringSliceCmd {
-	if w.isCluster {
-		return w.ClusterClient.SMembers(ctx, key)
-	}
 	return w.Client.SMembers(ctx, key)
 }
 
 func (w *redisClientWrapper) ZRangeWithScores(ctx context.Context, key string, start, stop int64) *redis.ZSliceCmd {
-	if w.isCluster {
-		return w.ClusterClient.ZRangeWithScores(ctx, key, start, stop)
-	}
 	return w.Client.ZRangeWithScores(ctx, key, start, stop)
 }
 
 func (w *redisClientWrapper) HGetAll(ctx context.Context, key string) *redis.MapStringStringCmd {
-	if w.isCluster {
-		return w.ClusterClient.HGetAll(ctx, key)
-	}
 	return w.Client.HGetAll(ctx, key)
 }
 
 func (w *redisClientWrapper) SlowLogGet(ctx context.Context, count int64) *redis.SlowLogCmd {
-	if w.isCluster {
-		return w.ClusterClient.SlowLogGet(ctx, count)
-	}
 	return w.Client.SlowLogGet(ctx, count)
 }
 
 func (w *redisClientWrapper) ClientList(ctx context.Context) *redis.StringCmd {
-	if w.isCluster {
-		return w.ClusterClient.ClientList(ctx)
-	}
 	return w.Client.ClientList(ctx)
 }
 
 func (w *redisClientWrapper) Do(ctx context.Context, args ...interface{}) *redis.Cmd {
-	if w.isCluster {
-		return w.ClusterClient.Do(ctx, args...)
-	}
 	return w.Client.Do(ctx, args...)
 }
 
 func (w *redisClientWrapper) Set(ctx context.Context, key string, value interface{}, expiration time.Duration) *redis.StatusCmd {
-	if w.isCluster {
-		return w.ClusterClient.Set(ctx, key, value, expiration)
-	}
 	return w.Client.Set(ctx, key, value, expiration)
 }
 
 func (w *redisClientWrapper) RPush(ctx context.Context, key string, values ...interface{}) *redis.IntCmd {
-	if w.isCluster {
-		return w.ClusterClient.RPush(ctx, key, values...)
-	}
 	return w.Client.RPush(ctx, key, values...)
 }
 
 func (w *redisClientWrapper) SAdd(ctx context.Context, key string, members ...interface{}) *redis.IntCmd {
-	if w.isCluster {
-		return w.ClusterClient.SAdd(ctx, key, members...)
-	}
 	return w.Client.SAdd(ctx, key, members...)
 }
 
 func (w *redisClientWrapper) HSet(ctx context.Context, key string, values ...interface{}) *redis.IntCmd {
-	if w.isCluster {
-		return w.ClusterClient.HSet(ctx, key, values...)
-	}
 	return w.Client.HSet(ctx, key, values...)
 }
 
 func (w *redisClientWrapper) Expire(ctx context.Context, key string, expiration time.Duration) *redis.BoolCmd {
-	if w.isCluster {
-		return w.ClusterClient.Expire(ctx, key, expiration)
-	}
 	return w.Client.Expire(ctx, key, expiration)
 }
 
 func (w *redisClientWrapper) Del(ctx context.Context, keys ...string) *redis.IntCmd {
-	if w.isCluster {
-		return w.ClusterClient.Del(ctx, keys...)
-	}
 	return w.Client.Del(ctx, keys...)
 }
 
 func (w *redisClientWrapper) LLen(ctx context.Context, key string) *redis.IntCmd {
-	if w.isCluster {
-		return w.ClusterClient.LLen(ctx, key)
-	}
 	return w.Client.LLen(ctx, key)
 }
 
 func (w *redisClientWrapper) SCard(ctx context.Context, key string) *redis.IntCmd {
-	if w.isCluster {
-		return w.ClusterClient.SCard(ctx, key)
-	}
 	return w.Client.SCard(ctx, key)
 }
 
 func (w *redisClientWrapper) SScan(ctx context.Context, key string, cursor uint64, match string, count int64) *redis.ScanCmd {
-	if w.isCluster {
-		return w.ClusterClient.SScan(ctx, key, cursor, match, count)
-	}
 	return w.Client.SScan(ctx, key, cursor, match, count)
 }
 
@@ -250,23 +156,10 @@ func getRedisClient(instance *model.Instance, db int) (*redisClientWrapper, erro
 	}
 	addr := fmt.Sprintf("%s:%d", instance.Host, instance.Port)
 
-	// Check cluster mode
-	isCluster := instance.ClusterMode != nil && *instance.ClusterMode
-
-	if isCluster {
-		clusterClient := redis.NewClusterClient(&redis.ClusterOptions{
-			Addrs:    []string{addr},
-			Password: password,
-		})
-		ctx := context.Background()
-		if err := clusterClient.Ping(ctx).Err(); err != nil {
-			clusterClient.Close()
-			return nil, fmt.Errorf("Redis Cluster connection failed: %v", err)
-		}
-		return &redisClientWrapper{ClusterClient: clusterClient, isCluster: true}, nil
-	}
-
-	// Standalone mode
+	// Always use single-node connection for query execution.
+	// ClusterClient does topology discovery (CLUSTER SLOTS) which fails when
+	// internal cluster IPs are unreachable from the client (e.g., Docker networks).
+	// Single-node mode works for all read-only commands on cluster nodes.
 	client := redis.NewClient(&redis.Options{
 		Addr:     addr,
 		Password: password,
@@ -277,7 +170,10 @@ func getRedisClient(instance *model.Instance, db int) (*redisClientWrapper, erro
 		client.Close()
 		return nil, fmt.Errorf("Redis connection failed: %v", err)
 	}
-	return &redisClientWrapper{Client: client, isCluster: false}, nil
+
+	// Check cluster mode flag for wrapper behavior (ScanAllKeys needs to know)
+	isCluster := instance.ClusterMode != nil && *instance.ClusterMode
+	return &redisClientWrapper{Client: client, isCluster: isCluster}, nil
 }
 
 // GET /api/v1/redis/:id/info