- sites.AskHandler now approves <name>.AGENTBBS_HOST on-demand-TLS when <name>
is a registered member (so only real users mint subdomain certs).
- Caddyfile: *.${DOMAIN} block serving users/<name>/public_html with on_demand
TLS; unknown users 404. Needs a wildcard DNS record *.${DOMAIN} -> host.
- Test: TestAskUserSubdomain.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>