API is running.

--- Infrastructure / diagnostics ---
  GET  /                         This index
  GET  /health                   Liveness probe — returns "ok"
  GET  /api                      JSON diagnostic info (config, URLs, issues)
  GET  /api/check          ?shop=  Readiness for a specific shop (token + feature flags)
  GET  /api/redirect-url         Full OAuth redirect URL

--- 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 (X-DSS-Internal-Secret header required if configured) ---
  PUT  /stores/api-key                          Set Shopify Admin token (see repo openapi.json)
  POST /sync-shipments-with-fulfillments        Monolith webhook: SyncShipmentsWithFulfillmentsRequest → sync Shopify fulfillments
  POST /tracking-update                         Monolith webhook: TrackingUpdateRequest → Shopify FulfillmentEvent
  POST /tracking-updates                        Alias for /tracking-update (same TrackingUpdateRequest body)

--- Demo routes (disabled — set ENABLE_DEMO_ROUTES=true) ---
  GET  /demo/products              ?shop=     List products via Shopify Graphql
  GET  /demo/order                 ?shop=&id=  Load a single order by GID or numeric ID
  POST /demo/fulfillment/create                 Create a fulfillment with tracking
  POST /demo/fulfillment/tracking               Update fulfillment tracking info