fix(backend): resolve TR json serialization, news concurrency and asset index locks

FinlyticAssets/Migrations/20260815184053_UpdateDynamicSettingsUniqueIndex.cs

@@ -1,4 +1,4 @@
-using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Migrations;
 
 #nullable disable
 
@@ -10,6 +10,11 @@ namespace FinlyticAssets.Migrations
         /// <inheritdoc />
         protected override void Up(MigrationBuilder migrationBuilder)
         {
+            migrationBuilder.Sql(@"
+                DELETE FROM ""DynamicSettings"" a USING ""DynamicSettings"" b
+                WHERE a.""Key"" = b.""Key"" AND a.""Id"" < b.""Id"";
+            ");
+
             migrationBuilder.DropIndex(
                 name: "IX_DynamicSettings_Key",
                 table: "DynamicSettings");