Prevent user to open multiple strategy on the same ticker

src/Managing.Application/ManageBot/StartCopyTradingCommandHandler.cs

@@ -72,6 +72,15 @@ namespace Managing.Application.ManageBot
                 throw new InvalidOperationException($"Could not retrieve configuration for master bot {request.MasterBotIdentifier}");
             }
 
+            // Check if user already has a bot on this ticker (same as master bot)
+            var hasExistingBotOnTicker = await _botService.HasUserBotOnTickerAsync(request.User.Id, masterConfig.Ticker);
+            if (hasExistingBotOnTicker)
+            {
+                throw new InvalidOperationException(
+                    $"You already have a strategy running or saved on ticker {masterConfig.Ticker}. " +
+                    "You cannot create multiple strategies on the same ticker.");
+            }
+
             // Get account information from the requesting user's accounts
             var userAccounts = await _accountService.GetAccountsByUserAsync(request.User, true, true);
             var firstAccount = userAccounts.FirstOrDefault();