Runtime/tooling: add a headless simulation service mode for automation

[devallibus]

Summary

A headless simulation service mode would give automation a stable way to inspect and drive a gametau project without depending on a browser or desktop shell.

Why this matters

• It creates a simple integration surface for agents and external tools.
• It makes simulation inspection and scripted workflows easier to run in local automation and CI.
• It can reuse the same core logic while avoiding UI/runtime setup costs.

Suggested scope

• Start with a local-only headless mode.
• Expose a minimal transport such as JSON over stdin/stdout, local HTTP, or a similarly simple interface.
• Focus on inspect/step/query operations before broader remote-control features.

Candidate capabilities

• Initialize/reset simulation
• Step ticks or run bounded scenarios
• Query stable world/state views
• Emit structured diagnostics and result payloads

Acceptance criteria

• At least one example or scaffolded project can run in headless simulation mode.
• The interface is documented and machine-readable.
• The mode is clearly scoped as a local tooling surface, not a production network service by default.
• The implementation composes with the existing core/runtime split.