Add MTA-STS support for alias domains (#6972)

* Initial plan

* Add MTA-STS support for alias domains

Co-authored-by: DerLinkman <62480600+DerLinkman@users.noreply.github.com>

* Improve domain normalization and code style in mta-sts.php

Co-authored-by: DerLinkman <62480600+DerLinkman@users.noreply.github.com>

* Add error handling for idn_to_ascii in mta-sts.php

Co-authored-by: DerLinkman <62480600+DerLinkman@users.noreply.github.com>

* Add database error handling for alias domain query

Co-authored-by: DerLinkman <62480600+DerLinkman@users.noreply.github.com>

* Add ACME certificate support for MTA-STS on alias domains

Query alias_domain table to find aliases with MTA-STS enabled target domains and request certificates for mta-sts.<alias-domain> subdomains.

Co-authored-by: DerLinkman <62480600+DerLinkman@users.noreply.github.com>

* compose: bump image tag to 1.95

* Add MTA-STS DNS records display for alias domains in UI

When viewing an alias domain's DNS diagnostics, check if the target domain has MTA-STS enabled and display the required DNS records for the alias domain.

Co-authored-by: DerLinkman <62480600+DerLinkman@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: DerLinkman <62480600+DerLinkman@users.noreply.github.com>
Co-authored-by: DerLinkman <niklas.meyer@servercow.de>

docker-compose.yml

@@ -465,7 +465,7 @@ services:
           condition: service_started
         unbound-mailcow:
           condition: service_healthy
-      image: ghcr.io/mailcow/acme:1.94
+      image: ghcr.io/mailcow/acme:1.95
       dns:
         - ${IPV4_NETWORK:-172.22.1}.254
       environment: