feat(adminfinance): 新增预计收入指标并优化明细查询性能

- 财务看板增加预计收入与待结算订单数统计
- 明细列表 COUNT 改为仅扫描 rental_orders 主表，避免 5-JOIN 子查询
- 统一前后端结算差异判定阈值为常量 5 分
- 修复日期选择器使用 UTC 日期导致东八区凌晨偏移前一天的问题

backend/internal/modules/adminfinance/dashboard.go

@@ -62,6 +62,18 @@ func (r *Repository) summary(ctx context.Context, query DashboardQuery) (*Financ
 		return nil, err
 	}
 
+	// 预计收入:尚未结算订单的下单预估平台手续费之和,按下单时间落在查询区间内统计。
+	var estimated estimatedIncomeRow
+	if err := db.Table("rental_orders").
+		Select(`COALESCE(SUM(platform_fee_cent), 0) AS estimated_income_amount_cent,
+			COUNT(id) AS pending_settle_order_count`).
+		Where("settlement_status NOT IN ?", settledSettlementStatuses()).
+		Where("status NOT IN ?", nonBillableOrderStatuses()).
+		Where("created_at >= ? AND created_at <= ?", query.StartDate, query.EndDate).
+		Scan(&estimated).Error; err != nil {
+		return nil, err
+	}
+
 	return &FinanceSummaryDTO{
 		TotalFlowAmountCent:         payment.TotalFlowAmountCent,
 		TotalRefundAmountCent:       payment.TotalRefundAmountCent,
@@ -71,10 +83,12 @@ func (r *Repository) summary(ctx context.Context, query DashboardQuery) (*Financ
 		OwnerShouldIncomeAmountCent: settlement.OwnerShouldIncomeAmountCent,
 		OwnerWalletIncomeAmountCent: settlement.OwnerWalletIncomeAmountCent,
 		SettlementDiffAmountCent:    settlement.OwnerShouldIncomeAmountCent - settlement.OwnerWalletIncomeAmountCent,
+		EstimatedIncomeAmountCent:   estimated.EstimatedIncomeAmountCent,
 		SuccessfulPayCount:          payment.SuccessfulPayCount,
 		SuccessfulRefundCount:       payment.SuccessfulRefundCount,
 		PendingRefundCount:          payment.PendingRefundCount,
 		SettledOrderCount:           settlement.SettledOrderCount,
+		PendingSettleOrderCount:     estimated.PendingSettleOrderCount,
 		FinancialExceptionCount:     exceptionCount,
 	}, nil
 }
@@ -112,6 +126,19 @@ func (r *Repository) dailyItems(ctx context.Context, query DashboardQuery) ([]Fi
 		return nil, err
 	}
 
+	// 每日预计收入:尚未结算订单的下单预估平台手续费,按下单日期归集,口径与 summary 一致。
+	estimates := make([]dailyEstimatedRow, 0)
+	if err := db.Table("rental_orders").
+		Select(`DATE(created_at) AS date,
+				COALESCE(SUM(platform_fee_cent), 0) AS estimated_income_amount_cent`).
+		Where("settlement_status NOT IN ?", settledSettlementStatuses()).
+		Where("status NOT IN ?", nonBillableOrderStatuses()).
+		Where("created_at >= ? AND created_at <= ?", query.StartDate, query.EndDate).
+		Group("DATE(created_at)").
+		Scan(&estimates).Error; err != nil {
+		return nil, err
+	}
+
 	itemsByDate := make(map[string]FinanceDailyDTO)
 	for day := dayStart(query.StartDate); !day.After(query.EndDate); day = day.AddDate(0, 0, 1) {
 		date := day.Format("2006-01-02")
@@ -141,6 +168,13 @@ func (r *Repository) dailyItems(ctx context.Context, query DashboardQuery) ([]Fi
 		item.SettledOrderCount = row.SettledOrderCount
 		itemsByDate[date] = item
 	}
+	for _, row := range estimates {
+		date := dailyDateKey(row.Date)
+		item := itemsByDate[date]
+		item.Date = date
+		item.EstimatedIncomeAmountCent = row.EstimatedIncomeAmountCent
+		itemsByDate[date] = item
+	}
 
 	items := make([]FinanceDailyDTO, 0, len(itemsByDate))
 	for day := dayStart(query.StartDate); !day.After(query.EndDate); day = day.AddDate(0, 0, 1) {
@@ -165,6 +199,11 @@ type settlementSummaryRow struct {
 	SettledOrderCount           int64
 }
 
+type estimatedIncomeRow struct {
+	EstimatedIncomeAmountCent int64
+	PendingSettleOrderCount   int64
+}
+
 type dailyPaymentRow struct {
 	Date                    string
 	TotalFlowAmountCent     int64
@@ -182,3 +221,8 @@ type dailySettlementRow struct {
 	OwnerWalletIncomeAmountCent int64
 	SettledOrderCount           int64
 }
+
+type dailyEstimatedRow struct {
+	Date                      string
+	EstimatedIncomeAmountCent int64
+}