COOLIFY_URL/COOLIFY_FQDN were custom variables requiring manual setup,
causing VITE_BACKEND_WS_URL to resolve to wss://backend/graphql (broken).
SERVICE_FQDN_HOPPSCOTCH_80 triggers Coolify auto-generation of an editable
domain, and SERVICE_URL_HOPPSCOTCH provides the scheme-less form needed for
the wss:// WebSocket URL.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
