feat: implement Part D and E from FIXPLAN

- D1/D2/D2c: Added TraderTraits entity, TraderTraitCalculator, Market Return Metrics (MedianWin, AvgWin, etc.), and trait filters
- D3: Implemented HF-Trader Tiering via IngestMode (Full, Aggregated, SnapshotOnly) and updated TradeHistoryWorker to respect tiers
- E1-E5: Added MasterStatus to Trader, TraderWindowMetrics for rolling analytics, Fingerprint metrics (PriceBandProfile, P50/P90), Copyability aggregates (Volume, Drift, Edge)
- E6: Implemented GET /api/traders/{id}/profile and GET /api/traders/correlation
- Replaced FIXPLAN-2026-07-09.md with FIXPLAN-TODO.md and FIXPLAN-DONE.md
- Cleaned up API docs and plan to use generic terms (removed hardcoded PolyTrader references)
- Added respective EF Core Migrations

src/Predictalytics.Domain/Entities/Trade.cs

@@ -79,6 +79,12 @@ public class Trade
     /// <summary>Indicates if high-res price context was fetched.</summary>
     public bool IsContextEnriched { get; set; }
 
+    /// <summary>
+    /// For aggregated trades (compacted history or HF trader hourly bucket), this stores 
+    /// the number of original trades that were grouped into this single row. Null means 1.
+    /// </summary>
+    public int? AggregatedCount { get; set; }
+
     // ── Transient (not persisted) ──────────────────────────────────────────
 
     /// <summary>
@@ -87,7 +93,13 @@ public class Trade
     /// </summary>
     [NotMapped]
     public string? TransientWallet { get; set; }
-    [NotMapped] public string? TransientDisplayName { get; set; }
+    
+    /// <summary>
+    /// Transient reference to the trader's display name from the platform, used to opportunistically 
+    /// update the local name if it's currently a placeholder or empty.
+    /// </summary>
+    [NotMapped] 
+    public string? TransientDisplayName { get; set; }
 
     // ── Navigation ────────────────────────────────────────────────────────
     public Trader Trader { get; set; } = null!;