Phase 5.3-ClosedTrade: ClosedTrade -> Modul + ICopyTradeLogRepository

- ClosedTrade (+ ClosedTradeRow) nach src/PolyTrader.Modules.CopyTrading/Models/.
- Neues ICopyTradeLogRepository (+ Mongo-Impl) im Modul: EnsureIndexes, Exists,
  Insert, Find(predicate) auf der closed_trades-Collection.
- closed_trades-Zugriffe der Modul-Services vom App-Shim auf das Repo umgestellt:
  TraderMonitorService, PersistenceService, PolymarketWssClient, TraderAnalyticsJob.
  Shim-/DB-Usings dort entfernt.
- TraderMonitorService nutzt kein _db mehr (auch die uebrigen _db-Guards aus 3d
  entfernt, da Repos immer verfuegbar sind). Verhaltensneutral.
- frm_main (UI) + Program.cs (BsonDocument-Cleanup) bleiben auf _db.
- Build 0 Fehler.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/PolyTrader.Modules.CopyTrading/Models/ClosedTrade.cs

@@ -0,0 +1,36 @@
+namespace PolyTraderSharp.Models
+{
+    public class ClosedTrade
+    {
+        [MongoDB.Bson.Serialization.Attributes.BsonId] public int TradeId { get; set; }
+        public int AccountId { get; set; }
+        public int SourceTraderId { get; set; }
+        public bool IsDemo { get; set; }
+
+        public string TokenId { get; set; } = string.Empty;
+        public string MarketSlug { get; set; } = string.Empty;
+        public string MarketQuestion { get; set; } = string.Empty;
+        public string Outcome { get; set; } = string.Empty;
+
+        public string Side { get; set; } = string.Empty;
+        public decimal EntryPrice { get; set; }
+        public decimal ExitPrice { get; set; }
+        public decimal Size { get; set; }
+
+        public decimal RealizedPnl { get; set; }
+        public decimal PnlPercent { get; set; }
+        public decimal TotalFees { get; set; }
+
+        public DateTime OpenedAt { get; set; }
+        public DateTime ClosedAt { get; set; }
+        public string ExitReason { get; set; } = string.Empty;
+    }
+    public class ClosedTradeRow : ClosedTrade
+    {
+        public string AccountName { get; set; } = string.Empty;
+        public string SourceTraderName { get; set; } = string.Empty;
+        
+        [System.ComponentModel.Browsable(false)]
+        public string SourceTraderAddress { get; set; } = string.Empty;
+    }
+}

src/PolyTrader.Modules.CopyTrading/Persistence/ICopyTradeLogRepository.cs

@@ -0,0 +1,25 @@
+using System;
+using System.Collections.Generic;
+using System.Linq.Expressions;
+using PolyTraderSharp.Models;
+
+namespace PolyTrader.Modules.CopyTrading.Persistence
+{
+    /// <summary>
+    /// Copytrading-eigener Trade-Log (Collection "closed_trades"). Enthält die kopierten,
+    /// geschlossenen Trades mit Copytrading-Details (SourceTraderId etc.).
+    /// Ergänzt später den generischen Core-Trade-Log (TradeRecord).
+    /// </summary>
+    public interface ICopyTradeLogRepository
+    {
+        void EnsureIndexes();
+
+        /// <summary>Prüft, ob für Account + TokenId bereits ein Eintrag existiert (Dedup).</summary>
+        bool Exists(int accountId, string tokenId);
+
+        void Insert(ClosedTrade trade);
+
+        /// <summary>Generische Abfrage (ersetzt die bisherigen LiteFind-Zugriffe).</summary>
+        List<ClosedTrade> Find(Expression<Func<ClosedTrade, bool>> predicate);
+    }
+}

src/PolyTrader.Modules.CopyTrading/Persistence/MongoCopyTradeLogRepository.cs

@@ -0,0 +1,45 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
+using MongoDB.Driver;
+using PolyTraderSharp.Models;
+
+namespace PolyTrader.Modules.CopyTrading.Persistence
+{
+    public class MongoCopyTradeLogRepository : ICopyTradeLogRepository
+    {
+        private readonly IMongoCollection<ClosedTrade> _col;
+
+        public MongoCopyTradeLogRepository(IMongoDatabase db)
+        {
+            _col = db.GetCollection<ClosedTrade>("closed_trades");
+        }
+
+        public void EnsureIndexes()
+        {
+            CreateIndex(x => x.TradeId);
+            CreateIndex(x => x.AccountId);
+            CreateIndex(x => x.TokenId);
+            CreateIndex(x => x.SourceTraderId);
+        }
+
+        private void CreateIndex(Expression<Func<ClosedTrade, object>> field)
+        {
+            try
+            {
+                var keys = Builders<ClosedTrade>.IndexKeys.Ascending(field);
+                _col.Indexes.CreateOne(new CreateIndexModel<ClosedTrade>(keys));
+            }
+            catch { }
+        }
+
+        public bool Exists(int accountId, string tokenId) =>
+            _col.Find(x => x.AccountId == accountId && x.TokenId == tokenId).Any();
+
+        public void Insert(ClosedTrade trade) => _col.InsertOne(trade);
+
+        public List<ClosedTrade> Find(Expression<Func<ClosedTrade, bool>> predicate) =>
+            _col.Find(predicate).ToList();
+    }
+}