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}

pkg/geoip/geoip.go

@@ -2,6 +2,7 @@
 package geoip
 
 import (
+	"errors"
 	"fmt"
 	"log/slog"
 	"net"
@@ -138,7 +139,7 @@ func InitGeoIP(provider string) {
 // GetGeoInfo looks up geographic information for ip using the active provider.
 func GetGeoInfo(ip net.IP) (*GeoInfo, error) {
 	if ip == nil {
-		return nil, fmt.Errorf("IP address cannot be nil")
+		return nil, errors.New("IP address cannot be nil")
 	}
 	provider := getProvider()
 	cacheKey := provider.Name() + ":" + ip.String()
@@ -157,7 +158,7 @@ func GetGeoInfo(ip net.IP) (*GeoInfo, error) {
 // LookupGeoInfoWithProvider looks up geographic information using a temporary provider.
 func LookupGeoInfoWithProvider(providerName string, ip net.IP) (*GeoInfo, error) {
 	if ip == nil {
-		return nil, fmt.Errorf("IP address cannot be nil")
+		return nil, errors.New("IP address cannot be nil")
 	}
 
 	provider, err := providerFactory(normalizeProvider(providerName))