enh(shopware): improve healthchecks and proxy configuration

Removed obsolete EXPOSE/healthcheck from Dockerfile and added robust service-specific healthchecks:

- web: HTTP robots.txt check

- worker/scheduler: php -v runtime check

- opensearch: cluster health API check

Added TRUSTED_PROXIES=* for proxy-aware headers and centralized OPENSEARCH_PORT in vars.

Context: discussed implementation details in ChatGPT conversation on 2025-11-06 — https://chatgpt.com/share/690c9fb3-79f4-800f-bbdf-ea370c8f142c

roles/web-app-shopware/templates/env.j2

@@ -5,7 +5,7 @@ APP_DEBUG="{{ MODE_DEBUG | ternary(1, 0) }}"
 
 # Shopware
 APP_ENV={{ 'dev' if (ENVIRONMENT | lower) == 'development' else 'prod' }}
-#TRUSTED_PROXIES=127.0.0.1
+TRUSTED_PROXIES=*
 INSTANCE_ID={{ application_id }}
 
 # Database
@@ -22,10 +22,10 @@ CACHE_URL="file://cache"
 
 {% if SHOPWARE_OPENSEARCH_ENABLED %}
 # Search
-ELASTICSEARCH_URL="http://opensearch:9200"
-OPENSEARCH_URL="http://opensearch:9200"
+ELASTICSEARCH_URL="http://opensearch:{{ SHOPWARE_OPENSEARCH_PORT }}"
+OPENSEARCH_URL="http://opensearch:{{ SHOPWARE_OPENSEARCH_PORT }}"
 OPENSEARCH_HOST="opensearch"
-OPENSEARCH_PORT_NUMBER="9200"
+OPENSEARCH_PORT_NUMBER="{{ SHOPWARE_OPENSEARCH_PORT }}"
 OPENSEARCH_INITIAL_ADMIN_PASSWORD="{{ users.administrator.password }}"
 {% endif %}