Nothing important

Not much of a problem but util-iso.sh doesn't take $iso_name from profiledef.sh, but writes "cachyos" in hard.

`util-iso.sh: mv "$outFolder/$_profile/cachyos-$(date --date="@${SOURCE_DATE_EPOCH:-$(date +%s)}" +%Y.%m.%d)-x86_64.iso" "$outFolder/$_profile/${iso_file}"`

Gave me have an error when modifying $iso_name to reflect the fact I made a few modifications.

```
[mkarchiso] INFO: Done!
3.3G /home/niidhogg/git/cachyos-archiso/out/desktop/cachyos-niidhoggmod-2026.05.31-x86_64.iso
mv: cannot stat '/home/niidhogg/git/cachyos-archiso/out/desktop/cachyos-2026.05.31-x86_64.iso': No such file or directory
==> ERROR: An unknown error has occurred. Exiting...

```