Feat: Add CRUD operations for Shader files via MCP

[Tanichael]

This pull request introduces a new tool within the MCP bridge for managing Unity shader files directly from an external process.

Motivation

To enable external build tools, content pipelines, or automated scripts to create, read, update, and delete Unity shader assets programmatically without direct user interaction with the Unity Editor UI. This enhances automation capabilities for shader development workflows.

Key Changes

• New ManageShader class: Added a dedicated class (UnityMcpBridge.Editor.Tools.ManageShader) to handle shader-specific operations.
• CRUD Actions: Implements the core HandleCommand method to support the following actions:
  • create: Creates a new .shader file. Accepts optional initial content (plain text or Base64 encoded). Generates default shader content if none is provided.
  • read: Reads the content of an existing .shader file. Returns plain text content and also Base64 encoded content if the file is large.
  • update: Overwrites the content of an existing .shader file. Requires content to be provided.
  • delete: Deletes a .shader file using AssetDatabase.DeleteAsset.
• Path Handling: Correctly resolves file paths relative to the Assets/ directory. Defaults to placing new shaders in a "Shaders" subdirectory if no path is specified. Handles forward and backslashes.
• Name Validation: Includes basic validation for the provided shader name.
• Base64 Support: Added utility methods (EncodeBase64, DecodeBase64) to handle potentially large shader contents efficiently via Base64 encoding in the request/response payload.
• Unity Integration: Utilizes AssetDatabase.ImportAsset and AssetDatabase.DeleteAsset to ensure Unity's asset database is correctly updated after file operations.
• Error Handling: Provides specific error responses for file not found, file already exists, invalid parameters, file system errors, and decoding failures.

This addition significantly expands the MCP bridge's functionality, providing robust external control over shader assets.

Please review the changes.

[bhadrik]

I have created agent inside of Unity instead of managing MCP, check it out here.
https://github.com/bhadrik/unity-autopilot