清理冗余的梯度返佣(TierCommission)配置

- 移除 Model 层：删除 ShopSeriesCommissionTier 模型及相关字段
- 更新 DTO：删除 TierCommissionConfig、TierEntry 类型及相关请求/响应字段
- 删除 Store 层：移除 ShopSeriesCommissionTierStore 及相关查询逻辑
- 简化 Service 层：删除梯度返佣处理逻辑，统计查询移除 tier_bonus 字段
- 数据库迁移：创建 000034_remove_tier_commission 移除相关表和字段
- 更新测试：移除梯度返佣相关测试用例，更新集成测试
- OpenAPI 文档：删除梯度返佣相关 schema 和枚举值
- 归档变更：归档 remove-tier-commission-redundancy 到 archive/2026-01-30-
- 同步规范：更新 4 个主 specs，标记废弃功能并添加迁移指引

原因：梯度返佣功能与一次性梯度佣金功能重复，且从未实现实际计算逻辑
迁移：使用一次性佣金的梯度模式 (OneTimeCommissionConfig.type = "tiered") 替代

internal/store/postgres/commission_record_store.go

@@ -96,14 +96,12 @@ func (s *CommissionRecordStore) ListByShopID(ctx context.Context, opts *store.Qu
 }
 
 type CommissionStats struct {
-	TotalAmount     int64
-	CostDiffAmount  int64
-	OneTimeAmount   int64
-	TierBonusAmount int64
-	TotalCount      int64
-	CostDiffCount   int64
-	OneTimeCount    int64
-	TierBonusCount  int64
+	TotalAmount    int64
+	CostDiffAmount int64
+	OneTimeAmount  int64
+	TotalCount     int64
+	CostDiffCount  int64
+	OneTimeCount   int64
 }
 
 func (s *CommissionRecordStore) GetStats(ctx context.Context, filters *CommissionRecordListFilters) (*CommissionStats, error) {
@@ -128,11 +126,9 @@ func (s *CommissionRecordStore) GetStats(ctx context.Context, filters *Commissio
 		COALESCE(SUM(amount), 0) as total_amount,
 		COALESCE(SUM(CASE WHEN commission_source = 'cost_diff' THEN amount ELSE 0 END), 0) as cost_diff_amount,
 		COALESCE(SUM(CASE WHEN commission_source = 'one_time' THEN amount ELSE 0 END), 0) as one_time_amount,
-		COALESCE(SUM(CASE WHEN commission_source = 'tier_bonus' THEN amount ELSE 0 END), 0) as tier_bonus_amount,
 		COUNT(*) as total_count,
 		COALESCE(SUM(CASE WHEN commission_source = 'cost_diff' THEN 1 ELSE 0 END), 0) as cost_diff_count,
-		COALESCE(SUM(CASE WHEN commission_source = 'one_time' THEN 1 ELSE 0 END), 0) as one_time_count,
-		COALESCE(SUM(CASE WHEN commission_source = 'tier_bonus' THEN 1 ELSE 0 END), 0) as tier_bonus_count
+		COALESCE(SUM(CASE WHEN commission_source = 'one_time' THEN 1 ELSE 0 END), 0) as one_time_count
 	`).Scan(&stats)
 
 	if result.Error != nil {

internal/store/postgres/shop_series_commission_tier_store.go

@@ -1,53 +0,0 @@
-package postgres
-
-import (
-	"context"
-
-	"github.com/break/junhong_cmp_fiber/internal/model"
-	"gorm.io/gorm"
-)
-
-type ShopSeriesCommissionTierStore struct {
-	db *gorm.DB
-}
-
-func NewShopSeriesCommissionTierStore(db *gorm.DB) *ShopSeriesCommissionTierStore {
-	return &ShopSeriesCommissionTierStore{db: db}
-}
-
-func (s *ShopSeriesCommissionTierStore) Create(ctx context.Context, tier *model.ShopSeriesCommissionTier) error {
-	return s.db.WithContext(ctx).Create(tier).Error
-}
-
-func (s *ShopSeriesCommissionTierStore) GetByID(ctx context.Context, id uint) (*model.ShopSeriesCommissionTier, error) {
-	var tier model.ShopSeriesCommissionTier
-	if err := s.db.WithContext(ctx).First(&tier, id).Error; err != nil {
-		return nil, err
-	}
-	return &tier, nil
-}
-
-func (s *ShopSeriesCommissionTierStore) Update(ctx context.Context, tier *model.ShopSeriesCommissionTier) error {
-	return s.db.WithContext(ctx).Save(tier).Error
-}
-
-func (s *ShopSeriesCommissionTierStore) Delete(ctx context.Context, id uint) error {
-	return s.db.WithContext(ctx).Delete(&model.ShopSeriesCommissionTier{}, id).Error
-}
-
-func (s *ShopSeriesCommissionTierStore) ListByAllocationID(ctx context.Context, allocationID uint) ([]*model.ShopSeriesCommissionTier, error) {
-	var tiers []*model.ShopSeriesCommissionTier
-	if err := s.db.WithContext(ctx).
-		Where("allocation_id = ?", allocationID).
-		Order("threshold_value ASC").
-		Find(&tiers).Error; err != nil {
-		return nil, err
-	}
-	return tiers, nil
-}
-
-func (s *ShopSeriesCommissionTierStore) DeleteByAllocationID(ctx context.Context, allocationID uint) error {
-	return s.db.WithContext(ctx).
-		Where("allocation_id = ?", allocationID).
-		Delete(&model.ShopSeriesCommissionTier{}).Error
-}