Fix phpMyAdmin SSO login and harden SSO/security posture

phpMyAdmin login was broken because phpmyadmin_install.sh never wired
the private phpMyAdmin copy into the web server: no Apache Alias was
registered via DirectAdmin CustomBuild, so the SSO redirect target was
unreachable. Add configure_apache_alias()/apply_apache_alias() (Alias +
Directory blocks, ./build rewrite_confs, httpd reload), detect the real
Apache group instead of hardcoding diradmin:diradmin, stop silently
swallowing chown/chmod failures, and verify an optional SHA256 for the
downloaded phpMyAdmin tarball. Extend phpmyadmin_health_check.sh to
detect a missing/incorrect Apache alias and to probe HTTP reachability.

Security hardening: scope temporary phpMyAdmin SSO MySQL roles to
127.0.0.1 instead of '%', tighten SSO ticket file permissions to 0640
(they contain a plaintext MySQL password), and log MySQL connection
failures for diagnosis instead of swallowing them silently.

Bump version to 1.2.12 and rebuild the release archive.

exec/lib/PhpMyAdminSso.php

@@ -155,7 +155,7 @@ final class PhpMyAdminSso
         if (@file_put_contents($tmpPath, $encoded, LOCK_EX) === false) {
             throw new RuntimeException('Nie udało się zapisać ticketu phpMyAdmin.');
         }
-        @chmod($tmpPath, 0644);
+        @chmod($tmpPath, 0640);
         if (!@rename($tmpPath, $path)) {
             @unlink($tmpPath);
             throw new RuntimeException('Nie udało się aktywować ticketu phpMyAdmin.');