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/repository/analytics/node_observability.go

@@ -5,6 +5,7 @@ package analytics
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"slices"
 	"time"
@@ -16,7 +17,7 @@ import (
 
 func observabilityConn() (driver.Conn, error) {
 	if db.ChConn == nil {
-		return nil, fmt.Errorf("clickhouse connection is not initialized")
+		return nil, errors.New("clickhouse connection is not initialized")
 	}
 	return db.ChConn, nil
 }