Passing custom Godot CLI arguments

[Dluckxx]

This pull request adds support for passing custom Godot CLI arguments when running a project through the MCP server, making it easier to trigger headless runs, specify main scenes, or use feature flags directly from your IDE. The changes include updates to the API schema, the server logic, and documentation to describe the new capability and its safety checks.

New feature: Custom Godot CLI arguments

• Updated the API schema for the run_project command to accept an optional extraArgs array, allowing users to specify additional CLI arguments for the Godot executable.
• Added logic in the server to parse, sanitize, and append custom CLI arguments from extraArgs, while filtering out disallowed flags like --path and -p to prevent conflicts. [1] [2]

Documentation improvements

• Updated README.md to describe how to use the new extraArgs option, including example payloads and safety notes about argument filtering.

[tylerstraub]

Just noting here that I had to make a similar modification in my custom local branch. But I also had to include tool support for multiple instances of processes in order to make the workflow coherent for situations like dedicated client/server with multiple clients that can spawn etc.

[tylerstraub]

I just decided to PR the experimental changes for the maintainers to see the example use case: #56

This is relevant here because it also involved adding CLI launch arg support.

[Dluckxx]

I just decided to PR the experimental changes for the maintainers to see the example use case: #56

This is relevant here because it also involved adding CLI launch arg support.

That's a great point regarding the client/server workflow. I hadn't considered the need for multiple instances when adding the CLI args, but it makes total sense.

I'll head over to #56 to review your approach. If your PR covers the CLI args implementation effectively along with the instance management, I'd be happy to defer to that one or help align this logic with yours to avoid conflicts.