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/oauth/cache.go

@@ -5,6 +5,7 @@ package oauth
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"strconv"
 	"sync"
@@ -140,7 +141,7 @@ func GetCachedToken(ctx context.Context, tokenHash string) (*model.AccessToken,
 			return &token, nil
 		}
 	}
-	return nil, fmt.Errorf("cache miss")
+	return nil, errors.New("cache miss")
 }
 
 // SetCachedToken 设置 AccessToken 缓存
@@ -183,7 +184,7 @@ func GetCachedUser(ctx context.Context, userID uint64) (*model.User, error) {
 			return &u, nil
 		}
 	}
-	return nil, fmt.Errorf("cache miss")
+	return nil, errors.New("cache miss")
 }
 
 // SetCachedUser 设置 User 缓存