feat: 新增配额包/支付相关实体与迁移

App：新增 operation_logs/quota_packages/tenant_payments/tenant_quota_package_purchases 表

Identity：修正 Avatar 字段类型（varchar(256)->text），保持现有数据不变

src/Application/TakeoutSaaS.Application/App/Statistics/Handlers/GetRevenueStatisticsQueryHandler.cs

@@ -0,0 +1,71 @@
+using MediatR;
+using TakeoutSaaS.Application.App.Statistics.Dto;
+using TakeoutSaaS.Application.App.Statistics.Queries;
+using TakeoutSaaS.Domain.Tenants.Repositories;
+
+namespace TakeoutSaaS.Application.App.Statistics.Handlers;
+
+/// <summary>
+/// 获取收入统计处理器。
+/// </summary>
+public sealed class GetRevenueStatisticsQueryHandler(IStatisticsRepository statisticsRepository)
+    : IRequestHandler<GetRevenueStatisticsQuery, RevenueStatisticsDto>
+{
+    /// <inheritdoc />
+    public async Task<RevenueStatisticsDto> Handle(GetRevenueStatisticsQuery request, CancellationToken cancellationToken)
+    {
+        var now = DateTime.UtcNow;
+        var currentMonth = new DateTime(now.Year, now.Month, 1);
+        var currentQuarter = GetQuarterStart(now);
+        var startMonth = currentMonth.AddMonths(-request.MonthsCount + 1);
+
+        // 查询所有已付款的账单
+        var bills = await statisticsRepository.GetPaidBillsAsync(cancellationToken);
+
+        // 总收入
+        var totalRevenue = bills.Sum(b => b.AmountPaid);
+
+        // 本月收入
+        var monthlyRevenue = bills
+            .Where(b => b.PeriodStart >= currentMonth)
+            .Sum(b => b.AmountPaid);
+
+        // 本季度收入
+        var quarterlyRevenue = bills
+            .Where(b => b.PeriodStart >= currentQuarter)
+            .Sum(b => b.AmountPaid);
+
+        // 月度收入明细
+        var monthlyDetails = bills
+            .Where(b => b.PeriodStart >= startMonth)
+            .GroupBy(b => new { b.PeriodStart.Year, b.PeriodStart.Month })
+            .Select(g => new MonthlyRevenueItem
+            {
+                Year = g.Key.Year,
+                Month = g.Key.Month,
+                Amount = g.Sum(b => b.AmountPaid),
+                BillCount = g.Count()
+            })
+            .OrderBy(m => m.Year)
+            .ThenBy(m => m.Month)
+            .ToList();
+
+        return new RevenueStatisticsDto
+        {
+            TotalRevenue = totalRevenue,
+            MonthlyRevenue = monthlyRevenue,
+            QuarterlyRevenue = quarterlyRevenue,
+            MonthlyDetails = monthlyDetails
+        };
+    }
+
+    /// <summary>
+    /// 获取季度开始时间。
+    /// </summary>
+    private static DateTime GetQuarterStart(DateTime date)
+    {
+        var quarter = (date.Month - 1) / 3;
+        var quarterStartMonth = quarter * 3 + 1;
+        return new DateTime(date.Year, quarterStartMonth, 1);
+    }
+}