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/07-parity-checklist.md

@@ -0,0 +1,28 @@
+# The Parity checklist
+
+`Type:` grilling (HITL)
+`Status:` open
+`Blocked by:` 05, 06
+
+Part of [the map](../map.md).
+
+## Question
+
+What exactly must the Storefront be able to do before the Theme store's pages are retired?
+
+Phase 5's gate is "the parity checklist is met", which is circular until the checklist exists. Enumerate it and settle what is genuinely required versus merely nice:
+
+- Guest checkout, and confirmation that no account is ever needed to buy.
+- Discount codes, per whatever the configuration check found.
+- Gifting, per the gifting model.
+- Shipping and delivery options as a buyer experiences them. India-only is settled; what is shown about it is not.
+- Order confirmation and transactional email, which Shopify sends but which currently carries the Theme store's branding.
+- Order history, which depends on Phase 4 — so decide whether Phase 4 gates this or merely improves it.
+- Search, and whether the existing predictive search is sufficient.
+- Anything else a buyer can currently do on `shop.mozimo.in` that mozimo.in cannot.
+
+For each item, mark whether it gates retirement or is deferred. Anything that gates retirement has to be finished before Phase 5, so this checklist sets the real scope of Phase 3.
+
+## Answer
+
+<!-- filled on resolution -->