Standardize nginx setup in install scripts

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.

install/2fauth-install.sh

@@ -49,6 +49,7 @@ chmod -R 755 /opt/2fauth
 msg_ok "Setup 2fauth"
 
 msg_info "Configure Service"
+PHP_SOCK=$(get_php_fpm_socket)
 cat <<EOF >/etc/nginx/conf.d/2fauth.conf
 server {
         listen 80;
@@ -67,7 +68,7 @@ server {
         error_page 404 /index.php;
 
         location ~ \.php\$ {
-                fastcgi_pass unix:/var/run/php/php${PHP_VERSION}-fpm.sock;
+                fastcgi_pass unix:${PHP_SOCK};
                 fastcgi_param SCRIPT_FILENAME \$realpath_root\$fastcgi_script_name;
                 include fastcgi_params;
         }