Add FileInputBot for non-interactive debugging and fix NbtToString crash

FileInputBot (ChatBots/FileInputBot.cs):
- New ChatBot that monitors a text file (default: mcc_input.txt) for
  commands, enabling MCC control from Cursor Shell or any non-interactive
  environment where stdin is not available
- Activated by setting MCC_FILE_INPUT env var (e.g. MCC_FILE_INPUT=1)
- Polls every ~500ms for new lines appended to the file
- Lines starting with "/" are sent as server chat/commands
- Other lines are executed as MCC internal commands (same as console input)
- File path overridable via MCC_INPUT_FILE env var

McClient.cs:
- Load FileInputBot when MCC_FILE_INPUT environment variable is set

ChatParser.cs - NbtToString:
- Fix InvalidCastException when NBT "text" or nameless root tag values
  are Int32 instead of String (happens with 1.20.6 SystemChat packets
  containing numeric values in the chat component tree)
- Replace direct (string) casts with ?.ToString() ?? string.Empty

Made-with: Cursor

MinecraftClient/ChatBots/FileInputBot.cs

@@ -0,0 +1,105 @@
+using System;
+using System.IO;
+using System.Threading;
+using MinecraftClient.CommandHandler;
+using MinecraftClient.Scripting;
+
+namespace MinecraftClient.ChatBots
+{
+    /// <summary>
+    /// Debug-only ChatBot that monitors a text file for commands.
+    /// Write lines to the file from any external tool (e.g. Cursor Shell)
+    /// and this bot will execute them as MCC internal commands.
+    ///
+    /// Usage from Cursor Shell:
+    ///   Add-Content mcc_input.txt "inventory"
+    ///   Add-Content mcc_input.txt "send /give @s diamond_sword 1"
+    ///
+    /// Lines starting with "/" are sent as server chat; others are treated
+    /// as MCC internal commands (same as typing in the MCC console).
+    /// </summary>
+    public class FileInputBot : ChatBot
+    {
+        private const string BotName = "FileInput";
+        private string _filePath = string.Empty;
+        private long _lastPosition;
+        private int _tickCounter;
+
+        public override void Initialize()
+        {
+            _filePath = Path.GetFullPath(
+                Environment.GetEnvironmentVariable("MCC_INPUT_FILE") ?? "mcc_input.txt");
+
+            if (File.Exists(_filePath))
+                _lastPosition = new FileInfo(_filePath).Length;
+            else
+                File.WriteAllText(_filePath, "");
+
+            LogToConsole(BotName, $"Watching: {_filePath}");
+            LogToConsole(BotName, "Write commands to this file to execute them.");
+        }
+
+        public override void Update()
+        {
+            // Poll every ~500ms (Update is called every ~100ms)
+            if (++_tickCounter < 5)
+                return;
+            _tickCounter = 0;
+
+            try
+            {
+                if (!File.Exists(_filePath))
+                    return;
+
+                var info = new FileInfo(_filePath);
+                if (info.Length <= _lastPosition)
+                    return;
+
+                string newContent;
+                using (var fs = new FileStream(_filePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
+                {
+                    fs.Seek(_lastPosition, SeekOrigin.Begin);
+                    using var reader = new StreamReader(fs);
+                    newContent = reader.ReadToEnd();
+                }
+                _lastPosition = info.Length;
+
+                foreach (var rawLine in newContent.Split('\n'))
+                {
+                    var line = rawLine.Trim();
+                    if (string.IsNullOrEmpty(line))
+                        continue;
+
+                    LogToConsole(BotName, $"> {line}");
+
+                    if (line.StartsWith("/"))
+                    {
+                        SendText(line);
+                    }
+                    else
+                    {
+                        CmdResult result = new();
+                        if (PerformInternalCommand(line, ref result))
+                        {
+                            if (!string.IsNullOrEmpty(result.ToString()))
+                                LogToConsole(BotName, result.ToString());
+                        }
+                        else
+                        {
+                            // Not an internal command — send as chat
+                            SendText(line);
+                        }
+                    }
+                }
+            }
+            catch (IOException)
+            {
+                // File may be temporarily locked by the writer
+            }
+            catch (Exception ex)
+            {
+                LogToConsole(BotName, $"Error: {ex.Message}");
+            }
+        }
+    }
+}

MinecraftClient/McClient.cs

@@ -425,8 +425,8 @@ namespace MinecraftClient
             if (Config.ChatBot.ScriptScheduler.Enabled) { BotLoad(new ScriptScheduler()); }
             if (Config.ChatBot.TelegramBridge.Enabled) { BotLoad(new TelegramBridge()); }
             if (Config.ChatBot.ItemsCollector.Enabled) { BotLoad(new ItemsCollector()); }
-            //Add your ChatBot here by uncommenting and adapting
-            //BotLoad(new ChatBots.YourBot());
+            if (!string.IsNullOrEmpty(Environment.GetEnvironmentVariable("MCC_FILE_INPUT")))
+                BotLoad(new FileInputBot());
         }
 
         /// <summary>

MinecraftClient/Protocol/Message/ChatParser.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
@@ -510,8 +510,7 @@ namespace MinecraftClient.Protocol.Message
         {
             if (nbt.Count == 1 && nbt.TryGetValue("", out object? rootMessage))
             {
-                // Nameless root tag
-                return (string)rootMessage;
+                return rootMessage?.ToString() ?? string.Empty;
             }
 
             string message = string.Empty;
@@ -526,7 +525,7 @@ namespace MinecraftClient.Protocol.Message
                 {
                     case "text":
                     {
-                        message = (string)value;
+                        message = value?.ToString() ?? string.Empty;
                     }
                         break;
                     case "extra":