Add ETH and USDC balance check before start/restart bot and autoswap

src/Managing.Core/Exceptions/CustomExceptions.cs

@@ -75,4 +75,79 @@ public class ServiceUnavailableException : Exception
     public ServiceUnavailableException(string message) : base(message)
     {
     }
+}
+
+/// <summary>
+/// Exception thrown when there are insufficient funds or allowance for a transaction
+/// This typically indicates the user needs to add more ETH for gas or approve token spending
+/// </summary>
+public class InsufficientFundsException : Exception
+{
+    /// <summary>
+    /// The type of insufficient funds error
+    /// </summary>
+    public InsufficientFundsType ErrorType { get; }
+
+    /// <summary>
+    /// User-friendly message explaining what needs to be done
+    /// </summary>
+    public string UserMessage { get; }
+
+    public InsufficientFundsException(string errorMessage, InsufficientFundsType errorType) 
+        : base(errorMessage)
+    {
+        ErrorType = errorType;
+        UserMessage = GetUserFriendlyMessage(errorType);
+    }
+
+    private static string GetUserFriendlyMessage(InsufficientFundsType errorType)
+    {
+        return errorType switch
+        {
+            InsufficientFundsType.InsufficientEth => 
+                "❌ **Insufficient ETH for Gas Fees**\n" +
+                "Your wallet doesn't have enough ETH to pay for transaction gas fees.\n" +
+                "Please add ETH to your wallet and try again.",
+            
+            InsufficientFundsType.InsufficientAllowance => 
+                "❌ **Insufficient Token Allowance**\n" +
+                "The trading contract doesn't have permission to spend your tokens.\n" +
+                "Please approve token spending in your wallet and try again.",
+            
+            InsufficientFundsType.InsufficientBalance => 
+                "❌ **Insufficient Token Balance**\n" +
+                "Your wallet doesn't have enough tokens for this trade.\n" +
+                "Please add more tokens to your wallet and try again.",
+            
+            _ => "❌ **Transaction Failed**\n" +
+                 "The transaction failed due to insufficient funds.\n" +
+                 "Please check your wallet balance and try again."
+        };
+    }
+}
+
+/// <summary>
+/// Types of insufficient funds errors
+/// </summary>
+public enum InsufficientFundsType
+{
+    /// <summary>
+    /// Not enough ETH for gas fees
+    /// </summary>
+    InsufficientEth,
+    
+    /// <summary>
+    /// Token allowance is insufficient (ERC20: transfer amount exceeds allowance)
+    /// </summary>
+    InsufficientAllowance,
+    
+    /// <summary>
+    /// Token balance is insufficient
+    /// </summary>
+    InsufficientBalance,
+    
+    /// <summary>
+    /// General insufficient funds error
+    /// </summary>
+    General
 }