fix: диагностика 502, /health и unit systemd для Caddy

Co-authored-by: Cursor <cursoragent@cursor.com>

deploy/caddy-after-shop.conf

@@ -0,0 +1,8 @@
+# Установка:
+#   mkdir -p /etc/systemd/system/caddy.service.d
+#   cp /opt/shop/deploy/caddy-after-shop.conf /etc/systemd/system/caddy.service.d/shop.conf
+#   systemctl daemon-reload
+
+[Unit]
+After=shop.service
+Wants=shop.service

deploy/shop.service

@@ -0,0 +1,20 @@
+[Unit]
+Description=Shop Node.js
+After=network.target
+
+[Service]
+Type=simple
+User=www-data
+Group=www-data
+WorkingDirectory=/opt/shop
+EnvironmentFile=/opt/shop/.env
+# Путь к node: which node  (часто /usr/bin/node)
+ExecStart=/usr/bin/node src/server.js
+Restart=on-failure
+RestartSec=5
+
+# Права на запись в data/ и node_modules (если нужно)
+UMask=0022
+
+[Install]
+WantedBy=multi-user.target