Run config.sh from Git checkout

This way, we don't have to rebuild the container image every time we
want to make a change to the configuration process.

config.sh

@@ -1,35 +1,10 @@
 #!/bin/sh
 
-: "${HOSTNAME:=$(hostname -f || uname -n)}"
-: "${DESTDIR=/host}"
-: "${KEYSERV_URL:=https://keyserv.pyrocufflink.blue}"
-: "${SSH_CERT:=${DESTDIR}/etc/ssh/ssh_host_ed25519_key-cert.pub}"
-: "${SSH_KEY:=${SSH_CERT%-cert.pub}}"
 : "${GIT_URL:=https://git.pyrocufflink.net/infra/cfg.git}"
 : "${GIT_BRANCH:=master}"
 
-printf 'Applying configuration policy for %s ...\n' "${HOSTNAME}"
-
 cd "$(mktemp -d)" || exit
 
 git clone --depth 1 "${GIT_URL}" -b "${GIT_BRANCH}" . || exit
 
-if [ -f host/"${HOSTNAME}".pre.sh ]; then
-    . host/"${HOSTNAME}".pre.sh
-fi
-
-curl -fsSL \
-    "${KEYSERV_URL}"/keys \
-    -H "Authorization: $(cat "${SSH_CERT}")" \
-    -o keys.age
-age -d -i "${SSH_KEY}" -o keys.txt keys.age
-
-if [ -f host/"${HOSTNAME}".cue ] && [ -f instructions/"${HOSTNAME}".cue ]; then
-    cue export host/"${HOSTNAME}".cue -o values.json || exit
-    cue export instructions/"${HOSTNAME}".cue -o instructions.json || exit
-    tmpl instructions.json values.json -d "${DESTDIR}" || exit
-fi
-
-if [ -f host/"${HOSTNAME}".post.sh ]; then
-    . host/"${HOSTNAME}".post.sh
-fi
+. ./config.sh