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/infra/persistence/redis.go

@@ -9,6 +9,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"log"
+	"strconv"
 	"strings"
 	"time"
 
@@ -83,7 +84,7 @@ func init() {
 	if err := redisotel.InstrumentTracing(
 		Redis,
 		redisotel.WithAttributes(
-			attribute.String("db.instance", fmt.Sprintf("%v", cfg.DB)),
+			attribute.String("db.instance", strconv.Itoa(cfg.DB)),
 			attribute.String("db.ip", strings.Join(cfg.Addrs, ",")),
 			attribute.String("db.system", "Redis"),
 		),