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/model/access_token.go

@@ -41,7 +41,7 @@ func GenerateTokenString() (string, error) {
 	if _, err := rand.Read(bytes); err != nil {
 		return "", err
 	}
-	return fmt.Sprintf("at_%s", hex.EncodeToString(bytes)), nil
+	return "at_" + hex.EncodeToString(bytes), nil
 }
 
 // HashToken 计算 Token 的 SHA-256 哈希值用于数据库存储与查询