perfsprint 18→0：strconv.Itoa/FormatInt/FormatUint/FormatBool 替代 fmt.Sprintf、无动词 fmt.Errorf→errors.New、纯字符串拼接。全部语义等价（已核对 diff）。修正 fixer 遗留的 import 问题（引入 goimports 统一整理）。

Result: {"status":"keep","total_issues":56,"golint_canonicalheader":8,"golint_errname":1,"golint_errorlint":12,"golint_forcetypeassert":3,"golint_gosec":0,"golint_intrange":3,"golint_modernize":5,"golint_nilnil":3,"golint_perfsprint":0,"golint_prealloc":3,"golint_recvcheck":7,"golint_usestdlibvars":3,"golint_wastedassign":7,"golint_total":55,"eslint_problems":1,"eslint_errors":0,"eslint_warnings":1,"tsc_errors":0,"measure_s":47}

internal/apps/openflare/relay/logics.go

@@ -5,6 +5,7 @@ package relay
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"strings"
 	"time"
@@ -20,7 +21,7 @@ const nodeStatusOnline = "online"
 // Heartbeat processes a relay heartbeat, updates node status, and returns config.
 func Heartbeat(ctx context.Context, node *model.OpenFlareNode, payload HeartbeatPayload) (*HeartbeatResponse, error) {
 	if node == nil {
-		return nil, fmt.Errorf("relay node is nil")
+		return nil, errors.New("relay node is nil")
 	}
 
 	payload.Version = strings.TrimSpace(payload.Version)