Wayfinder: chart the Shopify headless commerce map

The route from "mozimo.in displays Shopify products" to "mozimo.in sells them",
as a plan with a phase spine and gates, plus the open decision tickets that
still shape it and the evidence they rest on.

- .scratch/shopify-headless-commerce/: plan.md (phases and gates), map.md (the
  wayfinder map), 10 open decision tickets
- CONTEXT.md: Storefront / Theme store / Cart / Parity vocabulary
- docs/adr/0001-0003: Checkout stays Shopify-hosted, one Variant per product,
  the checkout domain stays shop.mozimo.in
- docs/research/ and docs/shopify-catalog-inventory.md: verified store facts,
  the Cart API probe, and the catalogue inventory

Raw Shopify doc scrapes under .scratch/shopify-research/ are ignored: they are
working material, not record.

.scratch/shopify-headless-commerce/issues/03-degraded-mode-experience.md

@@ -0,0 +1,22 @@
+# Degraded-mode experience
+
+`Type:` grilling (HITL)
+`Status:` open
+
+Part of [the map](../map.md).
+
+## Question
+
+When Shopify is unreachable, what does a buyer actually get?
+
+The Storefront currently falls back to the Editorial catalog, which is display-only and whose prices can drift from commerce truth. We decided that stale **real** data beats fabricated data, with buying disabled. This ticket settles what that means concretely:
+
+- When is degraded mode entered, and how is it detected — a failed Cart call, a failed product fetch, or both?
+- What does a buyer see? Does a notice appear, what does it say, and is it brand-appropriate for a luxury storefront?
+- Is stale data served transparently, or is the page visibly marked as out of date?
+- What exactly is disabled — the add-to-cart control, the Cart itself, or the route to Checkout?
+- What happens to an existing Cart mid-session when the API drops?
+
+## Answer
+
+<!-- filled on resolution -->