Add nginx configuration for Maho environment type

[fballiano]

This adds the nginx vhost template for the new maho environment type submitted in wardenenv/warden#941.

Maho is an open source ecommerce platform forked from OpenMage / Magento 1 and modernized with PHP 8.3+ support. I am its maintainer.

The template is based on magento1.conf:

• front controller routing to /index.php
• the same php-fpm fastcgi block, including the X-Rewrite-Url / X-Original-Url header blanking inherited from Magento 1
• commented MAGE_RUN_CODE / MAGE_RUN_TYPE params for multi-store setups (same convention as magento1.conf: the variables are not defined by the base server block, so they ship commented and users define and enable them per project when needed)

The /api routing follows Maho's public/.htaccess, which is the reference implementation:

• /api/rest/v2/* to rest.php (modern REST API, Symfony API Platform)
• /api/rest/* to api.php?type=rest (legacy Magento 1 REST, kept for compatibility)
• /api/soap, /api/v2_soap, /api/xmlrpc, /api/jsonrpc to index.php (legacy protocol dispatchers)
• any other /api/* (GraphQL, OpenAPI docs) to rest.php

Unlike Magento 1, Maho's webroot is the project's public/ directory (handled via NGINX_PUBLIC=/public in the environment definition), so the magento1.conf deny rules for app/, lib/, var/ etc. are not needed here: the application code lives outside the webroot. Deny rules for dotfiles and backup/config/source files are kept.

Verified by mounting this file into the published wardenenv/nginx:1.27 image with NGINX_TEMPLATE=maho.conf and NGINX_PUBLIC=/public, running the image's envsubst step and nginx -t (syntax ok, test successful).

Companion PRs:

• Add Maho environment support warden#941 (environment type)
• Add Maho environment type documentation docs#56 (documentation)