Add hard move limit variant rule

[Belzedar94]

Summary

• add variant configuration properties to support hard move limit adjudication
• end games automatically when the configured move hard limit is reached, respecting material counting or a custom value
• document the new configuration options in variants.ini

Testing

• make -j2 ARCH=x86-64 build

---

https://chatgpt.com/codex/tasks/task_e_68d12f89d8f08322bbed2bd486d1cb3e