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/model/dto/commission.go

@@ -11,7 +11,7 @@ type CommissionRecordResponse struct {
 	IotCardICCID     string `json:"iot_card_iccid" description:"卡ICCID"`
 	DeviceID         *uint  `json:"device_id" description:"关联设备ID"`
 	DeviceNo         string `json:"device_no" description:"设备号"`
-	CommissionSource string `json:"commission_source" description:"佣金来源 (cost_diff:成本价差, one_time:一次性佣金, tier_bonus:梯度奖励)"`
+	CommissionSource string `json:"commission_source" description:"佣金来源 (cost_diff:成本价差, one_time:一次性佣金)"`
 	Amount           int64  `json:"amount" description:"佣金金额（分）"`
 	BalanceAfter     int64  `json:"balance_after" description:"入账后钱包余额（分）"`
 	Status           int    `json:"status" description:"状态 (1:已入账, 2:已失效)"`
@@ -25,7 +25,7 @@ type CommissionRecordListRequest struct {
 	Page             int     `json:"page" query:"page" validate:"omitempty,min=1" minimum:"1" description:"页码"`
 	PageSize         int     `json:"page_size" query:"page_size" validate:"omitempty,min=1,max=100" minimum:"1" maximum:"100" description:"每页数量"`
 	ShopID           *uint   `json:"shop_id" query:"shop_id" validate:"omitempty" description:"店铺ID"`
-	CommissionSource *string `json:"commission_source" query:"commission_source" validate:"omitempty,oneof=cost_diff one_time tier_bonus" description:"佣金来源 (cost_diff:成本价差, one_time:一次性佣金, tier_bonus:梯度奖励)"`
+	CommissionSource *string `json:"commission_source" query:"commission_source" validate:"omitempty,oneof=cost_diff one_time" description:"佣金来源 (cost_diff:成本价差, one_time:一次性佣金)"`
 	StartTime        *string `json:"start_time" query:"start_time" validate:"omitempty" description:"开始时间"`
 	EndTime          *string `json:"end_time" query:"end_time" validate:"omitempty" description:"结束时间"`
 	Status           *int    `json:"status" query:"status" validate:"omitempty,oneof=1 2" description:"状态 (1:已入账, 2:已失效)"`
@@ -42,17 +42,14 @@ type CommissionRecordPageResult struct {
 
 // CommissionStatsResponse 佣金统计响应
 type CommissionStatsResponse struct {
-	TotalAmount      int64 `json:"total_amount" description:"总收入（分）"`
-	CostDiffAmount   int64 `json:"cost_diff_amount" description:"成本价差收入（分）"`
-	OneTimeAmount    int64 `json:"one_time_amount" description:"一次性佣金收入（分）"`
-	TierBonusAmount  int64 `json:"tier_bonus_amount" description:"梯度奖励收入（分）"`
-	CostDiffPercent  int64 `json:"cost_diff_percent" description:"成本价差占比（千分比）"`
-	OneTimePercent   int64 `json:"one_time_percent" description:"一次性佣金占比（千分比）"`
-	TierBonusPercent int64 `json:"tier_bonus_percent" description:"梯度奖励占比（千分比）"`
-	TotalCount       int64 `json:"total_count" description:"总笔数"`
-	CostDiffCount    int64 `json:"cost_diff_count" description:"成本价差笔数"`
-	OneTimeCount     int64 `json:"one_time_count" description:"一次性佣金笔数"`
-	TierBonusCount   int64 `json:"tier_bonus_count" description:"梯度奖励笔数"`
+	TotalAmount     int64 `json:"total_amount" description:"总收入（分）"`
+	CostDiffAmount  int64 `json:"cost_diff_amount" description:"成本价差收入（分）"`
+	OneTimeAmount   int64 `json:"one_time_amount" description:"一次性佣金收入（分）"`
+	CostDiffPercent int64 `json:"cost_diff_percent" description:"成本价差占比（千分比）"`
+	OneTimePercent  int64 `json:"one_time_percent" description:"一次性佣金占比（千分比）"`
+	TotalCount      int64 `json:"total_count" description:"总笔数"`
+	CostDiffCount   int64 `json:"cost_diff_count" description:"成本价差笔数"`
+	OneTimeCount    int64 `json:"one_time_count" description:"一次性佣金笔数"`
 }
 
 // DailyCommissionStatsResponse 每日佣金统计响应