strings in StringCategory can be reuse to prevent the generated files from being too large

https://github.com/synapticon/siitool/blob/c46570adb1228eada44ae1f38bd61a81fab99c98/sii.c#L196

<img width="514" height="776" alt="Image" src="https://github.com/user-attachments/assets/f455c179-6664-4843-b826-12240a7f2ef7" />