debug: 添加站点设置持久化调试日志，追踪 Set/Get 链路

internal/config/site_settings.go

@@ -1,6 +1,7 @@
 package config
 
 import (
+	"log"
 	"strconv"
 	"sync"
 
@@ -73,15 +74,19 @@ func (s *SiteSettings) GetBool(key string, defaultVal bool) bool {
 // Set 写入设置（同步写 DB + 更新内存，使用 UPSERT 兼容首次保存）
 func (s *SiteSettings) Set(key, value string) error {
 	entry := model.SiteSetting{Key: key, Value: value}
-	if err := s.db.Clauses(clause.OnConflict{
+	result := s.db.Clauses(clause.OnConflict{
 		Columns:   []clause.Column{{Name: "key"}},
 		DoUpdates: clause.AssignmentColumns([]string{"value"}),
-	}).Create(&entry).Error; err != nil {
-		return err
+	}).Create(&entry)
+	if result.Error != nil {
+		log.Printf("[SiteSettings] Set FAIL key=%s value=%s err=%v", key, value, result.Error)
+		return result.Error
 	}
 	s.mu.Lock()
+	oldVal, existed := s.data[key]
 	s.data[key] = value
 	s.mu.Unlock()
+	log.Printf("[SiteSettings] Set OK key=%s old=%q new=%q existed=%v rows=%d", key, oldVal, value, existed, result.RowsAffected)
 	return nil
 }