API is running.

--- Infrastructure / diagnostics ---
  GET  /                         This index
  GET  /health                   Health probe - JSON with status "ok" and the running version; 503 with status "warming_up" until the warm-up is done
  GET  /api                      JSON diagnostic info (config, URLs, issues)
  GET  /api/redirect-url         Full OAuth redirect URL

--- Webhook subscriptions (Authorization: Bearer <MONOLITH_TO_DSS_API_KEY> required) ---
  GET  /api/check          ?shop=  Readiness for a specific shop: token resolvable, access scopes, webhook subscriptions
  POST /api/webhooks/register?shop=  Register a shop's webhook subscriptions as an install does, deleting those for topics no longer handled

--- Shopify OAuth ---
  GET  /install            ?shop=  Start OAuth - redirects to Shopify authorize URL
  GET  /oauth/callback           OAuth callback - code exchange, saves token, registers webhooks

--- Webhooks ---
  POST /webhooks/shopify         Shopify webhook receiver (products/*, orders/*)

--- DSS Internal API (Authorization: Bearer <MONOLITH_TO_DSS_API_KEY> required) ---
  PUT  /stores/api-key                          Set Shopify Admin token (see the checked-in monolith contract)
  POST /sync-shipments-with-fulfillments        Monolith webhook: SyncShipmentsWithFulfillmentsRequest -> sync Shopify fulfillments
  POST /tracking-update                         Monolith webhook: TrackingUpdateRequest -> Shopify FulfillmentEvent