Fixed immediate value formatting in Group1 instruction handlers

TestDisassembler.cs

@@ -0,0 +1,44 @@
+using X86Disassembler.X86;
+
+namespace TestDisassembler;
+
+public class Program
+{
+    public static void Main(string[] args)
+    {
+        // Test the specific byte sequence that's causing issues
+        byte[] codeBytes = HexStringToByteArray("816B1078563412");
+        
+        // Create a disassembler with the code
+        Disassembler disassembler = new Disassembler(codeBytes, 0x1000);
+        
+        // Disassemble the code
+        var instructions = disassembler.Disassemble();
+        
+        // Print the number of instructions
+        Console.WriteLine($"Number of instructions: {instructions.Count}");
+        
+        // Print each instruction
+        for (int i = 0; i < instructions.Count; i++)
+        {
+            Console.WriteLine($"Instruction {i+1}: {instructions[i].Mnemonic} {instructions[i].Operands}");
+        }
+    }
+    
+    private static byte[] HexStringToByteArray(string hex)
+    {
+        // Remove any non-hex characters
+        hex = hex.Replace(" ", "").Replace("-", "");
+        
+        // Create a byte array
+        byte[] bytes = new byte[hex.Length / 2];
+        
+        // Convert each pair of hex characters to a byte
+        for (int i = 0; i < hex.Length; i += 2)
+        {
+            bytes[i / 2] = Convert.ToByte(hex.Substring(i, 2), 16);
+        }
+        
+        return bytes;
+    }
+}