feat(loyalty): add staff autocomplete to PIN management

When creating or editing a staff PIN in the store context, the name
field now shows an autocomplete dropdown with the store's team members
(loaded from GET /store/team/members). Selecting a member auto-fills
name and staff_id (email). The dropdown filters as you type.

Only active in store context (where staffApiPrefix is configured).
Merchant and admin PIN views are unaffected — merchant has no
staffApiPrefix, admin is read-only.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/modules/loyalty/static/store/js/loyalty-pins.js

@@ -6,6 +6,7 @@ const storePinsLog = window.LogConfig.loggers.storePins || window.LogConfig.crea
 function storeLoyaltyPins() {
     return loyaltyPinsList({
         apiPrefix: '/store/loyalty',
+        staffApiPrefix: '/store',
         showStoreFilter: false,
         showCrud: true,
         currentPage: 'pins',