feat: add run_server_code tool for server context execution

[kevinswint]

Summary

Adds new MCP tool to execute Luau code in the actual game server context during playtest, unlike run_code which executes in the plugin context.

Motivation

Currently, run_code executes in the plugin's Lua context, which is isolated from server-side game state during playtest. This means you can't:

• Verify if server scripts initialized properly
• Check _G values set by ServerScriptService scripts
• Test server-side functionality

This PR adds run_server_code which executes in the actual game server context.

New Tool: run_server_code

run_server_code({ code: "PING" })
run_server_code({ code: "return _G.PlayerDataStore" })  -- requires LoadStringEnabled

Architecture

• MCP server queues code commands at /mcp/server_code endpoint
• Game ServerScript (MCPServerCodeRunner.lua) polls for pending code
• Script executes code and POSTs results back
• Tool waits with 30s timeout

Setup

1. Copy MCPServerCodeRunner.lua to ServerScriptService in your game
2. Enable HttpService: Game Settings > Security > Allow HTTP Requests
3. Start playtest (F5)
4. Use the run_server_code tool

Built-in Commands (work without LoadStringEnabled)

• PING - Returns "pong" to verify script is running
• PLAYERS - Returns list of current players
• STATE - Returns server state info as JSON
• STOP - Stops the playtest

Test plan

• Verify tool returns error when not in playtest
• Verify tool returns error when MCPServerCodeRunner not present
• Verify tool executes code and returns result (PING → pong)
• Verify built-in commands work without LoadStringEnabled
• Verify 30s timeout works

🤖 Generated with Claude Code

[glocation87]

We need this! runtime read/write is good for testing and debugging;
However, It would also be nice to have an implementation for the client context as well, i think the runtime lua files should be initialized and created by the plugin itself before playtest,

Perhaps: