Add mcp:quickstart

[ashleyhindle]

What & Why

Adds a new mcp:quickstart artisan command which:

• Sets up routes/ai.php
• Creates a server
• Adds example Tool, Resource, and Prompt
• Registers the primitives to the server
• Registers the server in routes/ai.php
• Gives clear 'how to test' instructions

This is based on working with people to add MCP to their projects, and peering over their shoulder while they read our docs.

mcp:quickstart will improve that initial DX and path to the 'aha' moment.

How I tested

1. Used it a ton with Locket
2. Ran the tests

Notes/thoughts

• Once this is ready I need to write docs for laravel.com/docs/mcp