feat: add TradeContext, Subcategory and LastAnalyzedAt

src/Predictalytics.Domain/Entities/TraderCategoryPerformance.cs

@@ -11,6 +11,9 @@ public class TraderCategoryPerformance
 
     public MarketCategory Category { get; set; }
 
+    /// <summary>Subcategory (e.g. "Basketball", "Elections", "Bitcoin").</summary>
+    public string Subcategory { get; set; } = string.Empty;
+
     /// <summary>Total volume traded in this category (USD).</summary>
     public decimal TotalVolume { get; set; }