docs(llms): add MCP Unity overview

Introduce llms.txt describing MCP Unity as an open-source implementation of the Moet server library for Unity, including a reference to the WebSocket-Sharp C# library.

Author: CoderGamester

llms.txt

@@ -0,0 +1,46 @@
+# MCP Unity
+
+> MCP Unity is an open-source implementation of the Model Context Protocol (MCP) for the Unity Editor.
+> It connects a C# Unity Editor package with a Node.js/TypeScript server over WebSockets and exposes
+> high-level "tools" and "resources" so language-model agents and other automated clients can safely
+> inspect, test, and modify Unity projects in real-time.
+
+This repository consists of two coordinated halves that communicate using JSON-encoded MCP messages:
+
+- **Editor/** – Unity package that starts an internal WebSocket server and registers C# MCP tools & resources.
+- **Server/** – Node.js/TypeScript application that runs outside Unity, connects to the Editor server, and
+  re-exposes identical MCP tools/resources for AI assistants.
+
+Together they allow AI coding assistants (e.g. Windsurf, Cursor, Claude Code, GitHub Copilot) to drive the Unity Editor headlessly,
+automate scene and asset management, run tests, install packages, and gather diagnostics.
+
+## Docs
+- [Project README](README.md): Full feature list, installation, and getting-started guide.
+- [Installation guide](README.md#installation): Step-by-step setup instructions.
+- [Unity Editor Tools source](Editor/Tools/): C# classes that implement individual editor actions.
+- [Node.js Tools source](Server~/src/tools/): TypeScript wrappers that forward requests to Unity.
+
+## Tools
+- [`execute_menu_item`](README.md#mcp-server-tools): Executes Unity Editor menu items by path.
+- [`select_gameobject`](README.md#mcp-server-tools): Selects GameObjects in the Unity scene by path or instance ID.
+- [`update_gameobject`](README.md#mcp-server-tools): Creates or updates GameObjects (name, tag, layer, active/static).
+- [`update_component`](README.md#mcp-server-tools): Adds or edits component fields on GameObjects.
+- [`add_package`](README.md#mcp-server-tools): Installs Unity packages via the Package Manager.
+- [`run_tests`](README.md#mcp-server-tools): Runs Unity Test Runner tests (EditMode/PlayMode).
+- [`send_console_log`](README.md#mcp-server-tools): Sends a console message to the Unity Editor log.
+- [`add_asset_to_scene`](README.md#mcp-server-tools): Adds an AssetDatabase asset to the current scene.
+
+## Resources
+- [unity://menu-items](README.md#mcp-server-resources): Returns all available Unity menu items.
+- [unity://scenes-hierarchy](README.md#mcp-server-resources): Current scene hierarchy tree.
+- [unity://gameobject/{id}](README.md#mcp-server-resources): Detailed info for a specific GameObject.
+- [unity://logs](README.md#mcp-server-resources): Unity console log entries.
+- [unity://packages](README.md#mcp-server-resources): Installed/available Unity packages.
+- [unity://assets](README.md#mcp-server-resources): AssetDatabase search results.
+- [unity://tests/{testMode}](README.md#mcp-server-resources): Test metadata for EditMode/PlayMode.
+
+## Optional
+- [Model Context Protocol specification](https://modelcontextprotocol.io/spec): Formal protocol definition for MCP.
+- [Unity Editor](https://unity.com/releases/editor/archive): Official Unity Editor download and documentation.
+- [Node.js](https://nodejs.org/en/download/): JavaScript runtime used for the MCP server backend.
+- [WebSocket-Sharp (C#)](https://github.com/sta/websocket-sharp/tree/master/websocket-sharp/Server): C# WebSocket server library used in the Unity package.