feat: Add Native MCP Server documentation

[MichaelFisher1997]

Summary

Adds comprehensive documentation for the newly merged Native MCP Server module (PR godotengine#1154).

Changes

• Added tutorials/editor/mcp_server.rst: A detailed guide covering:
  • Overview of MCP and its capabilities.
  • Enabling the server via --mcp-server.
  • Configuration examples for OpenCode/Cursor (Standard & Nix).
  • Full reference for the 5 Master Controllers (scene_action, game_control, etc.).
  • Best practices for AI agents.
• Updated tutorials/editor/index.rst: Added mcp_server to the "Advanced features" section.

Verification

• Syntax follows standard ReStructuredText.
• Integrated into the editor tutorial section.

Summary by CodeRabbit

• Documentation
  • Added a comprehensive guide for Model Context Protocol (MCP) Server integration in the editor: setup for standard and Nix environments, master controller capabilities, agent best practices, and a verification workflow with examples and commands.
  • Added the MCP Server page into the editor learning/navigation flow.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

📝 Walkthrough

Walkthrough

Adds a new toctree entry in tutorials/editor/index.rst and a new tutorials/editor/mcp_server.rst documenting the embedded Model Context Protocol (MCP) server for the Redot editor: enablement, configuration, master controllers, agent best practices, debugging, and verification workflow.

Changes

Cohort / File(s)	Summary
Documentation: Editor TOC tutorials/editor/index.rst	Adds a toctree entry registering mcp_server under Advanced features.
Documentation: MCP Server Tutorial tutorials/editor/mcp_server.rst	New comprehensive tutorial for the MCP server: capabilities (vision, inspection, editing, input playback), headless enablement (--mcp-server), example configs (mcp.json), five master controllers (redot_scene_action, redot_resource_action, redot_code_intel, redot_project_config, redot_game_control), agent best practices, verification workflow (Python example), and Nix/engine contributor notes.

Sequence Diagram(s)

(omitted — changes are documentation-only)

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Poem

🐰 I nibble docs where MCP lights gleam,

Controllers hum and agents dream,
I hop through configs, scripts in tow,
Verifying states in tidy rows,
🥕 cheers for docs that help us grow.

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'feat: Add Native MCP Server documentation' directly and clearly describes the main change: adding documentation for the MCP Server module to the Redot editor tutorials.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

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