Phase 7: Tests erweitert + Mongo-Parser extrahiert (testbar)

Tests (jetzt 48 grün):
- DbContextMappingTests: sichert core_/mod_-Tabellennamen, Position-Composite-Key,
  TrackedTrader-Key, ClosedTradeRow nicht gemappt, AccountState.OpenPositions ignoriert.
- PositionRepositoryTests: Live/Demo-Trennung, Upsert setzt Account+Demo-Flag,
  Update ohne Duplikat, DeleteLive, DropDemo.
- MarketRepositoryTests: GetActive filtert Closed, Upsert-Update, FindByTokenId.
- TradeLogRepositoryTests: GetRecent (Sortierung+Limit), Find-Predikat, Guid-Id unique.
- MongoExportParserTests: String-Dezimale, null->"", fehlende Felder->Default,
  AssignedAccountIds-Array, Category-Default, Nicht-Array->leer.

Refactor:
- Mongo-Export-Parsing aus ConfigMigrator in testbare Klasse
  PolyTrader.Modules.CopyTrading.ConfigImport.MongoExportParser ausgelagert
  (ParseAccounts -> Account+Settings, ParseTraders). ConfigMigrator nutzt sie;
  --migrate-json end-to-end verifiziert (3/3/32).
- PolyTrader.App.csproj: tests/** vom Default-Glob ausgeschlossen (App zog sonst
  die Testdateien mit rein -> doppelte AssemblyInfo/Xunit-Fehler).

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

tests/PolyTrader.Tests/MongoExportParserTests.cs

@@ -0,0 +1,120 @@
+using System.Collections.Generic;
+using System.Linq;
+using PolyTrader.Modules.CopyTrading.ConfigImport;
+using Xunit;
+
+namespace PolyTrader.Tests
+{
+    /// <summary>
+    /// Sichert das robuste Parsen der mongoexport-JSON ab: Dezimalwerte als Strings,
+    /// null-Felder, fehlende Felder → Default, Account-Arrays.
+    /// </summary>
+    public class MongoExportParserTests
+    {
+        [Fact]
+        public void ParseAccounts_reads_core_fields_and_string_decimals()
+        {
+            const string json = """
+            [{
+              "_id": 1,
+              "Name": "Richard Test",
+              "WalletAddress": "0x628",
+              "IsDemo": false,
+              "IsActive": true,
+              "TotalBalance": "64.763626",
+              "AvailableBalance": "1.155226"
+            }]
+            """;
+
+            var imp = Assert.Single(MongoExportParser.ParseAccounts(json));
+            Assert.Equal(1, imp.Account.AccountId);
+            Assert.Equal("Richard Test", imp.Account.Name);
+            Assert.Equal("0x628", imp.Account.WalletAddress);
+            Assert.False(imp.Account.IsDemo);
+            Assert.True(imp.Account.IsActive);
+            Assert.Equal(64.763626m, imp.Account.TotalBalance);
+            Assert.Equal(1.155226m, imp.Account.AvailableBalance);
+        }
+
+        [Fact]
+        public void ParseAccounts_maps_old_limit_fields_into_settings()
+        {
+            const string json = """
+            [{ "_id": 3, "PerMarketLimit": "10", "PerMasterLimit": "20", "MaxBuyPrice": "0.85", "PreRedeemLimit": "99.5" }]
+            """;
+
+            var imp = Assert.Single(MongoExportParser.ParseAccounts(json));
+            Assert.Equal(3, imp.Settings.AccountId);
+            Assert.Equal(10m, imp.Settings.PerMarketLimit);
+            Assert.Equal(20m, imp.Settings.PerMasterLimit);
+            Assert.Equal(0.85m, imp.Settings.MaxBuyPrice);
+            Assert.Equal(99.5m, imp.Settings.PreRedeemLimit);
+        }
+
+        [Fact]
+        public void ParseAccounts_null_string_falls_back_to_empty()
+        {
+            const string json = """[{ "_id": 3, "PayoutAddress": null }]""";
+
+            var imp = Assert.Single(MongoExportParser.ParseAccounts(json));
+            Assert.Equal(string.Empty, imp.Account.PayoutAddress);
+        }
+
+        [Fact]
+        public void ParseAccounts_missing_settings_fields_use_defaults()
+        {
+            const string json = """[{ "_id": 1 }]""";
+
+            var imp = Assert.Single(MongoExportParser.ParseAccounts(json));
+            Assert.Equal(5.0m, imp.Settings.PerMarketLimit);
+            Assert.Equal(2.0m, imp.Settings.MaxPriceDifference);
+            Assert.Equal(0.98m, imp.Settings.MaxBuyPrice);
+            Assert.Equal(40.0m, imp.Settings.perMaxTimeNone);
+        }
+
+        [Fact]
+        public void ParseTraders_reads_fields_and_assigned_accounts()
+        {
+            const string json = """
+            [{
+              "_id": 2,
+              "WalletAddress": "0xa2711",
+              "DisplayName": "0xa2711",
+              "Category": "TRADING_BOT",
+              "IsActive": false,
+              "TotalTrades": 32,
+              "TotalPnl": 7386.655743958501,
+              "AssignedAccountIds": [1, 3],
+              "Description": null
+            }]
+            """;
+
+            var t = Assert.Single(MongoExportParser.ParseTraders(json));
+            Assert.Equal(2, t.Id);
+            Assert.Equal("TRADING_BOT", t.Category);
+            Assert.False(t.IsActive);
+            Assert.Equal(32, t.TotalTrades);
+            Assert.Equal(7386.655743958501, t.TotalPnl, 6);
+            Assert.Equal(new HashSet<int> { 1, 3 }, t.AssignedAccountIds);
+            Assert.Equal(string.Empty, t.Description);
+        }
+
+        [Fact]
+        public void ParseTraders_missing_category_uses_default()
+        {
+            const string json = """[{ "_id": 5, "DisplayName": "x" }]""";
+
+            var t = Assert.Single(MongoExportParser.ParseTraders(json));
+            Assert.Equal("NEW_BIG_BET", t.Category);
+            Assert.Empty(t.AssignedAccountIds);
+        }
+
+        [Fact]
+        public void Parse_returns_empty_for_non_array_or_empty()
+        {
+            Assert.Empty(MongoExportParser.ParseAccounts("{}"));
+            Assert.Empty(MongoExportParser.ParseAccounts("[]"));
+            Assert.Empty(MongoExportParser.ParseTraders("[]"));
+        }
+    }
+}