docs(openspec): fix group-buying archive scenario and address-book purpose

Rename the group-buying "Order lifecycle" cancel scenario to the exact name
the current order spec uses; a MODIFIED requirement replaces the whole block,
so the old name made archive refuse to drop the existing scenario.

Replace the placeholder Purpose in the archived address-book spec, which the
wave-7 archive left as TBD and strict validation rejected.

openspec validate --all --strict is green again.

openspec/changes/add-group-buying/specs/order/spec.md

@@ -30,7 +30,7 @@ Status transitions SHALL be: pending_payment → paid → fulfilling → shipped
 - **WHEN** payment fills the final available group seat
 - **THEN** the payment succeeds and the group state becomes successful
 
-#### Scenario: cancel restores stock without group rollback
+#### Scenario: cancel restores stock
 - **WHEN** a customer cancels a pending_payment group-intent order
 - **THEN** SKU stock increases by the ordered qty, status is cancelled, and no paid group membership is removed
 

openspec/specs/address-book/spec.md

@@ -1,7 +1,8 @@
 # address-book Specification
 
 ## Purpose
-TBD - created by archiving change replace-mock-api-wave-7. Update Purpose after archive.
+Let a signed-in customer keep a reusable book of shipping addresses: owner-scoped list, create, update and delete, plus exactly one database-enforced default per customer. Introduced when the mall's fixture address book was replaced with live data (replace-mock-api-wave-7); checkout still submits its own inline shipping-address snapshot rather than a saved address id.
+
 ## Requirements
 ### Requirement: Saved shipping addresses
 A customer SHALL be able to list, create, update and delete their own shipping addresses through the API. Every address operation SHALL be scoped to the authenticated customer; operating on another user's address SHALL return 404. Non-customer roles SHALL be rejected with 403.