Refactors many install scripts to use the shared `nginx_enable_site` helper instead of manual symlink/default-site/reload sequences, making webserver setup more consistent and less error-prone. It also replaces hardcoded PHP-FPM socket paths with `get_php_fpm_socket` (including templated substitutions where needed) across nginx and caddy configs to improve compatibility with varying PHP versions and socket locations.
PR #14818 replaced the setup wizard curl with CLI commands but omitted
the schema migration step, causing fresh installs to fail when creating
the admin user. Trigger schema init via HTTP after config-ini.
Fixes#15828
MickLesk