feat: 代理充值支持线下支付凭证上传与存储

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

internal/model/agent_wallet.go

@@ -79,6 +79,7 @@ type AgentRechargeRecord struct {
 	PaymentTransactionID *string        `gorm:"column:payment_transaction_id;type:varchar(100);comment:第三方支付交易号" json:"payment_transaction_id,omitempty"`
 	PaymentConfigID      *uint          `gorm:"column:payment_config_id;index;comment:支付配置ID(关联tb_wechat_config.id)" json:"payment_config_id,omitempty"`
 	Status               int            `gorm:"column:status;type:int;not null;default:1;comment:充值状态(1-待支付 2-已支付 3-已完成 4-已关闭 5-已退款)" json:"status"`
+	PaymentVoucherKey    string         `gorm:"column:payment_voucher_key;type:varchar(500);comment:支付凭证对象存储Key（线下支付时必填，微信支付时为空）" json:"payment_voucher_key,omitempty"`
 	PaidAt               *time.Time     `gorm:"column:paid_at;comment:支付时间" json:"paid_at,omitempty"`
 	CompletedAt          *time.Time     `gorm:"column:completed_at;comment:完成时间" json:"completed_at,omitempty"`
 	ShopIDTag            uint           `gorm:"column:shop_id_tag;not null;index;comment:店铺ID标签(多租户过滤)" json:"shop_id_tag"`