Fix installer

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

hosts/common/configs/system/nix-install/install.sh

@@ -54,7 +54,7 @@ set_password_file() {
       exit 1
     fi
 
-    ln -sf "$password_file" /tmp/installer.key
+    ln -sf "$(realpath "$password_file")" /tmp/installer.key
   else
     echo "Enter password for LUKS encryption:"
     IFS= read -r -s password
@@ -68,6 +68,7 @@ set_password_file() {
 
 prepare_disk() {
   local disko_mode="$1"
+  mkdir -p /mnt
   root=$(mktemp -d /mnt/install.XXXXXX)
   disko -m "$disko_mode" --yes-wipe-all-disks --root-mountpoint "$root" "$flake/hosts/$host/format.nix" --arg device "\"$device\""
 }