feat: 组合列表增加今日涨跌额和持仓数量

- PortfolioListItem 新增 TodayProfit、TodayProfitCurrency 字段
- GetPortfolios 计算今日盈亏（从净值历史）
- Tags 显示持仓数量（如 '运行中 · USD · 3只'）

AssetManager.Models/DTOs/PortfolioDTO.cs

@@ -176,6 +176,8 @@ public class PortfolioListItem
     public string? Currency { get; set; }
     public double ReturnRate { get; set; }
     public string? ReturnType { get; set; }
+    public double TodayProfit { get; set; }
+    public string? TodayProfitCurrency { get; set; }
 }
 
 /// <summary>

AssetManager.Services/PortfolioService.cs

@@ -172,21 +172,55 @@ public class PortfolioService : IPortfolioService
             .Where(p => p.UserId == userId)
             .ToList();
 
-        return portfolios.Select(p => new PortfolioListItem
+        var result = new List<PortfolioListItem>();
+        
+        foreach (var p in portfolios)
         {
-            Id = p.Id,
-            Name = p.Name,
-            Tags = $"{p.Status} · {p.Currency}",
-            Status = p.Status,
-            StatusType = p.Status == "运行中" ? "green" : "gray",
-            IconChar = p.Name?.Substring(0, 1).ToUpper() ?? "P",
-            IconBgClass = "bg-blue-100",
-            IconTextClass = "text-blue-700",
-            Value = (double)p.TotalValue,
-            Currency = p.Currency,
-            ReturnRate = (double)p.ReturnRate,
-            ReturnType = p.ReturnRate >= 0 ? "positive" : "negative"
-        }).ToList();
+            // 获取持仓数量
+            var positionCount = _db.Queryable<Position>()
+                .Where(pos => pos.PortfolioId == p.Id)
+                .Count();
+            
+            // 获取今日盈亏（从净值历史）
+            var todayNav = _db.Queryable<PortfolioNavHistory>()
+                .Where(n => n.PortfolioId == p.Id && n.NavDate == DateTime.Today)
+                .First();
+            
+            double todayProfit = 0;
+            if (todayNav != null && p.TotalValue > 0)
+            {
+                // 今日盈亏 = 今日市值 - 昨日市值
+                var yesterdayNav = _db.Queryable<PortfolioNavHistory>()
+                    .Where(n => n.PortfolioId == p.Id && n.NavDate < DateTime.Today)
+                    .OrderByDescending(n => n.NavDate)
+                    .First();
+                
+                if (yesterdayNav != null)
+                {
+                    todayProfit = (double)(todayNav.TotalValue - yesterdayNav.TotalValue);
+                }
+            }
+            
+            result.Add(new PortfolioListItem
+            {
+                Id = p.Id,
+                Name = p.Name,
+                Tags = $"{p.Status} · {p.Currency}" + (positionCount > 0 ? $" · {positionCount}只" : ""),
+                Status = p.Status,
+                StatusType = p.Status == "运行中" ? "green" : p.Status == "已暂停" ? "yellow" : "gray",
+                IconChar = p.Name?.Substring(0, 1).ToUpper() ?? "P",
+                IconBgClass = "bg-blue-100",
+                IconTextClass = "text-blue-700",
+                Value = (double)p.TotalValue,
+                Currency = p.Currency,
+                ReturnRate = (double)p.ReturnRate,
+                ReturnType = p.ReturnRate >= 0 ? "positive" : "negative",
+                TodayProfit = todayProfit,
+                TodayProfitCurrency = p.Currency
+            });
+        }
+        
+        return result;
     }
 
     public async Task<TotalAssetsResponse> GetTotalAssetsAsync(string userId)