fix(loyalty): wire merchant staff PIN form to team-member autocomplete

The shared loyalty pins list factory has an autocomplete-from-team
flow gated behind config.staffApiPrefix (loaded once into a list, then
filtered client-side). The merchant entry in static/merchant/js/loyalty-pins.js
never set staffApiPrefix, so the loadStaffMembers branch never ran and
the "Staff member name" field on /merchants/loyalty/pins fell back to
free text instead of suggesting actual team members.

Wire the merchant config to /merchants/account, and add a flat
GET /merchants/account/team/members alias next to the existing
/merchants/account/team that returns just {members: [...]} — matching
the shape the shared autocomplete factory already expects at
${prefix}/team/members.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

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

@@ -6,6 +6,7 @@ const merchantPinsLog = window.LogConfig.loggers.merchantPins || window.LogConfi
 function merchantLoyaltyPins() {
     return loyaltyPinsList({
         apiPrefix: '/merchants/loyalty',
+        staffApiPrefix: '/merchants/account',
         showStoreFilter: true,
         showCrud: true,
         currentPage: 'pins',