development-nightly-2026-06-08

fix(e2e): restore .htaccess after local/docker runs

The headless installer rewrites RewriteBase and the ErrorDocument 404
directive in the version-controlled phpmyfaq/.htaccess in place. bin/e2e
only backed up database.php, so every e2e run leaked the install artifact
(ErrorDocument 404 -> /index.php?action=404) into the working tree.

Generalize the backup/restore into backup_file/restore_file helpers and
snapshot .htaccess alongside database.php.