feat: 添加订单大厅看板 API（四列数据 + 统计 + 重连补偿 + 操作端点）

- 新增 OrderBoardCardDto、OrderBoardResultDto、OrderBoardStatsDto
- 新增看板查询 Query + Handler（board/stats/pending-since）
- IOrderRepository 扩展 GetActiveOrdersAsync、GetOrdersChangedSinceAsync
- EfOrderRepository 实现看板查询方法
- 新增 OrderBoardController（GET board/stats/pending-since + POST accept/reject/complete/confirm）
- 新增 RejectOrderRequest 契约

src/Application/TakeoutSaaS.Application/App/Orders/Handlers/GetOrderBoardQueryHandler.cs

@@ -0,0 +1,89 @@
+using MediatR;
+using TakeoutSaaS.Application.App.Orders.Dto;
+using TakeoutSaaS.Application.App.Orders.Queries;
+using TakeoutSaaS.Domain.Orders.Entities;
+using TakeoutSaaS.Domain.Orders.Enums;
+using TakeoutSaaS.Domain.Orders.Repositories;
+
+namespace TakeoutSaaS.Application.App.Orders.Handlers;
+
+/// <summary>
+/// 获取订单看板数据查询处理器。
+/// </summary>
+public sealed class GetOrderBoardQueryHandler(IOrderRepository orderRepository)
+    : IRequestHandler<GetOrderBoardQuery, OrderBoardResultDto>
+{
+    /// <inheritdoc />
+    public async Task<OrderBoardResultDto> Handle(GetOrderBoardQuery request, CancellationToken cancellationToken)
+    {
+        // 1. 查询活跃订单
+        var activeOrders = await orderRepository.GetActiveOrdersAsync(
+            request.TenantId, request.StoreId, cancellationToken);
+
+        // 2. 查询今日已完成订单（限 20 条）
+        var todayStart = DateTime.UtcNow.Date;
+        var completedOrders = await orderRepository.GetOrdersChangedSinceAsync(
+            request.TenantId, request.StoreId, todayStart, cancellationToken);
+        var todayCompleted = completedOrders
+            .Where(o => o.Status == OrderStatus.Completed)
+            .OrderByDescending(o => o.FinishedAt)
+            .Take(20)
+            .ToList();
+
+        // 3. 合并并按渠道筛选
+        var allOrders = activeOrders.Concat(todayCompleted).ToList();
+        if (request.Channel.HasValue)
+        {
+            allOrders = allOrders.Where(o => o.Channel == request.Channel.Value).ToList();
+        }
+
+        // 4. 获取商品摘要
+        var orderIds = allOrders.Select(o => o.Id).ToList();
+        var itemsMap = orderIds.Count > 0
+            ? await orderRepository.GetItemsByOrderIdsAsync(orderIds, request.TenantId, cancellationToken)
+            : new Dictionary<long, IReadOnlyList<OrderItem>>();
+
+        // 5. 按状态分组
+        var cards = allOrders.Select(o => MapToCard(o, itemsMap)).ToList();
+
+        return new OrderBoardResultDto
+        {
+            Pending = cards.Where(c => c.Status == OrderStatus.AwaitingPreparation)
+                .OrderBy(c => c.CreatedAt).ToList(),
+            Making = cards.Where(c => c.Status == OrderStatus.InProgress)
+                .OrderBy(c => c.AcceptedAt).ToList(),
+            Delivering = cards.Where(c => c.Status == OrderStatus.Ready)
+                .OrderBy(c => c.ReadyAt).ToList(),
+            Completed = cards.Where(c => c.Status == OrderStatus.Completed)
+                .OrderByDescending(c => c.CreatedAt).ToList()
+        };
+    }
+
+    private static OrderBoardCardDto MapToCard(
+        Order order,
+        IReadOnlyDictionary<long, IReadOnlyList<OrderItem>> itemsMap)
+    {
+        var items = itemsMap.TryGetValue(order.Id, out var list) ? list : [];
+        var summary = items.Count > 0
+            ? string.Join("、", items.Take(3).Select(x => x.ProductName))
+              + (items.Count > 3 ? $" 等{items.Count}件" : string.Empty)
+            : string.Empty;
+
+        return new OrderBoardCardDto
+        {
+            Id = order.Id,
+            OrderNo = order.OrderNo,
+            StoreId = order.StoreId,
+            Channel = order.Channel,
+            DeliveryType = order.DeliveryType,
+            Status = order.Status,
+            CustomerName = order.CustomerName,
+            CustomerPhone = order.CustomerPhone,
+            TableNo = order.TableNo,
+            QueueNumber = order.QueueNumber,
+            ItemsSummary = summary,
+            PaidAmount = order.PaidAmount,
+            CreatedAt = order.CreatedAt
+        };
+    }
+}