fix: nginx entrypoint - use sed instead of grep -oP for Alpine compat

main_dc/nginx/entrypoint.sh

@@ -21,7 +21,7 @@ for ssl_conf in "$CONF_AVAILABLE"/*.ssl.conf; do
   http_conf="$CONF_AVAILABLE/$base.http.conf"
 
   # CERT_DOMAIN в первой строке: # CERT_DOMAIN=example.ru
-  cert_domain="$(head -1 "$ssl_conf" | grep -oP '(?<=# CERT_DOMAIN=).+')" || true
+  cert_domain="$(head -1 "$ssl_conf" | sed -n 's/.*# CERT_DOMAIN=\(.*\)/\1/p')" || true
 
   if [ -n "$cert_domain" ] && [ -f "$CERT_DIR/$cert_domain/fullchain.pem" ]; then
     ln -sf "$ssl_conf" "$CONF_D/$base.ssl.conf"