fix(stability): 修复慢查询雪崩隐患、系统配置死锁与提号翻页错误

- 消除 system_configs 写锁争抢：使用读写锁与启动预热将默认配置初始化收敛为单例，杜绝读请求开事务导致的 Lock wait timeout exceeded
- 强化财务看板缓存：将 Redis 缓存有效期由 1 分钟延长为 5 分钟，接入 singleflight.Group 防并发击穿
- 修复提号列表 GORM 翻页 Bug：分离 Count 查询与列表查询构建，避免重复 Join 导致的 Error 1066
- 生产环境资源加固：docker-compose.prod.yml 中 MySQL 资源限制提升至 2.0 核 CPU、2G 内存
- 补充 systemconfig 并发测试与 pickup 分页 Count 回归测试

backend/internal/modules/pickup/repository.go

@@ -893,44 +893,46 @@ func (r *Repository) ListAvailableListings(ctx context.Context, query AvailableL
 		Select("listing_id, MAX(id) AS upload_id").
 		Where("listing_id IS NOT NULL").
 		Group("listing_id")
-	db := r.db.WithContext(ctx).Table("rental_listings AS l").
-		Select(`l.id, l.listing_no, l.account_id, l.owner_id, l.price_cent AS listing_price_cent,
-			a.title AS account_title, a.server_region, a.login_platform, a.haf_coin_amount, a.asset_summary,
-			owner.phone AS owner_phone, l.handoff_mode, l.settlement_mode,
-			CASE WHEN lu.id IS NULL THEN 0 ELSE 1 END AS is_external_upload,
-			COALESCE(lu.source_channel, '') AS source_channel`).
-		Joins("JOIN game_accounts AS a ON a.id = l.account_id").
-		Joins("JOIN users AS owner ON owner.id = l.owner_id").
-		Joins("LEFT JOIN (?) AS latest_upload ON latest_upload.listing_id = l.id", latestUploads).
-		Joins("LEFT JOIN listing_uploads AS lu ON lu.id = latest_upload.upload_id").
-		Where("l.status = ? AND l.review_status = ? AND l.in_transaction = ?", "published", "approved", false)
-	if kw := strings.TrimSpace(query.Keyword); kw != "" {
-		upper := strings.ToUpper(kw)
-		if strings.HasPrefix(upper, "L") || (len(kw) >= 12 && isAllDigits(kw)) {
-			db = db.Where("l.listing_no = ?", kw)
-		} else {
-			like := "%" + kw + "%"
-			db = db.Where("l.listing_no LIKE ? OR a.title LIKE ?", like, like)
+	buildQuery := func() *gorm.DB {
+		q := r.db.WithContext(ctx).Table("rental_listings AS l").
+			Joins("JOIN game_accounts AS a ON a.id = l.account_id").
+			Joins("JOIN users AS owner ON owner.id = l.owner_id").
+			Joins("LEFT JOIN (?) AS latest_upload ON latest_upload.listing_id = l.id", latestUploads).
+			Joins("LEFT JOIN listing_uploads AS lu ON lu.id = latest_upload.upload_id").
+			Where("l.status = ? AND l.review_status = ? AND l.in_transaction = ?", "published", "approved", false)
+		if kw := strings.TrimSpace(query.Keyword); kw != "" {
+			upper := strings.ToUpper(kw)
+			if strings.HasPrefix(upper, "L") || (len(kw) >= 12 && isAllDigits(kw)) {
+				q = q.Where("l.listing_no = ?", kw)
+			} else {
+				like := "%" + kw + "%"
+				q = q.Where("l.listing_no LIKE ? OR a.title LIKE ?", like, like)
+			}
 		}
-	}
-	switch strings.TrimSpace(query.SourceType) {
-	case ListingSourceExternal:
-		db = db.Where("lu.id IS NOT NULL")
-	case ListingSourceInternal:
-		db = db.Where("lu.id IS NULL")
+		switch strings.TrimSpace(query.SourceType) {
+		case ListingSourceExternal:
+			q = q.Where("lu.id IS NOT NULL")
+		case ListingSourceInternal:
+			q = q.Where("lu.id IS NULL")
+		}
+		return q
 	}
 
 	page, pageSize := normalizePaging(query.Page, query.PageSize)
 	var rows []availableListingRow
-	if err := db.Order("l.id DESC").Offset((page - 1) * pageSize).Limit(pageSize).Scan(&rows).Error; err != nil {
+	if err := buildQuery().Select(`l.id, l.listing_no, l.account_id, l.owner_id, l.price_cent AS listing_price_cent,
+			a.title AS account_title, a.server_region, a.login_platform, a.haf_coin_amount, a.asset_summary,
+			owner.phone AS owner_phone, l.handoff_mode, l.settlement_mode,
+			CASE WHEN lu.id IS NULL THEN 0 ELSE 1 END AS is_external_upload,
+			COALESCE(lu.source_channel, '') AS source_channel`).
+		Order("l.id DESC").Offset((page - 1) * pageSize).Limit(pageSize).Scan(&rows).Error; err != nil {
 		return nil, err
 	}
 	var total int64
 	if page == 1 && len(rows) < pageSize {
 		total = int64(len(rows))
 	} else {
-		countDB := db.Session(&gorm.Session{}).Select("l.id")
-		if err := countDB.Count(&total).Error; err != nil {
+		if err := buildQuery().Count(&total).Error; err != nil {
 			return nil, err
 		}
 	}

backend/internal/modules/pickup/repository_test.go

@@ -283,6 +283,19 @@ func TestRepositoryListAvailableListingsFiltersAccountSource(t *testing.T) {
 	if internalResult.Total != 1 || len(internalResult.Items) != 1 {
 		t.Fatalf("站内上传结果 = total %d, items %d, want 1", internalResult.Total, len(internalResult.Items))
 	}
+
+	// 验证分页场景（len(rows) == pageSize 或 page > 1）：触发独立 Count 查询，确保不会重复 Join 报错 Error 1066
+	pagedResult, err := repo.ListAvailableListings(t.Context(), AvailableListingQuery{
+		Page:     1,
+		PageSize: 1,
+	})
+	if err != nil {
+		t.Fatalf("分页查询触发 Count 失败: %v", err)
+	}
+	if pagedResult.Total != 2 || len(pagedResult.Items) != 1 {
+		t.Fatalf("分页结果 = total %d, items %d, want total 2, items 1", pagedResult.Total, len(pagedResult.Items))
+	}
+
 	internalItem := internalResult.Items[0]
 	if internalItem.ID != internal.ID || internalItem.IsExternalUpload || internalItem.AccountSource != AccountSourceInternal {
 		t.Fatalf("站内上传账号 = id %d, external %t, source %q", internalItem.ID, internalItem.IsExternalUpload, internalItem.AccountSource)