Adds an (access_log) snippet writing JSON-formatted access logs to
/var/log/caddy/access.log with 10mb rolling and 14-file retention. Both
archive vhosts (archiv.raddatz.cloud and staging.raddatz.cloud) import
it; the git vhost is intentionally excluded.
This is the prerequisite for the fail2ban jail committed in the next
commit — fail2ban tails this file looking for 401 responses on
/api/auth/login to defend against credential stuffing.
Validated with `caddy validate` against caddy:2.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>