Add dashboard performance trends

api/QuestionsApi/Models/DashboardModels.cs

@@ -32,6 +32,7 @@ public sealed class DashboardTrendPoint
     public int Correct { get; set; }
     public int Total { get; set; }
     public int Accuracy { get; set; }
+    public int? QuestionBankRating { get; set; }
 }
 
 public sealed class DashboardSystemPerformance

api/QuestionsApi/Models/QuestionAttempt.cs

@@ -19,6 +19,8 @@ public class QuestionAttempt
     public int DurationSeconds { get; set; }
     public int CounterBucket { get; set; }
     public bool? RatingApplied { get; set; }
+    public int? UserOverallEloAfter { get; set; }
+    public DateTime? RatingAppliedUtc { get; set; }
     public string RatingLeaseOwner { get; set; } = "";
     public DateTime RatingLeaseUntilUtc { get; set; }
     public DateTime CreatedUtc { get; set; } = DateTime.UtcNow;

api/QuestionsApi/Models/RatingModels.cs

@@ -13,6 +13,8 @@ public class UserRating
     public int OverallElo { get; set; } = 1000;
     public Dictionary<string, int> CategoryElos { get; set; } = [];
     public int RatedQuestionCount { get; set; }
+    public int? HistoryBaselineElo { get; set; }
+    public DateTime? HistoryStartedUtc { get; set; }
     public DateTime UpdatedUtc { get; set; } = DateTime.UtcNow;
 }