Use config file.

Root password must be set, otherwise it will always prompt and never
install the root ssh key.

User creation fails on Debian 14 (Forky) because it does not contain
adduser (only useradd). It will hang until rebooted. And because of that
hang, the timezone is also not applied.

.gitattributes

@@ -5,6 +5,7 @@
 *.sh text eol=lf
 *.keys text eol=lf
 *.pub text eol=lf
+*.config text eol=lf
 
 *.txt text eol=lf
 *.md text eol=lf

opi-six.config

@@ -0,0 +1,7 @@
+PRESET_NET_CHANGE_DEFAULTS="1"
+PRESET_NET_ETHERNET_ENABLED="1"
+PRESET_LOCALE="en_US.UTF-8"
+PRESET_TIMEZONE="Europe/Zurich"
+PRESET_ROOT_PASSWORD=""
+PRESET_ROOT_KEY="https://gitea.dellenba.ch/infra/public_keys/raw/branch/main/root@opi-six.pub"
+SET_LANG_BASED_ON_LOCATION=n