refactor(loyalty): use search_autocomplete macro for terminal lookup

Replace custom inline autocomplete HTML with the shared
search_autocomplete macro from inputs.html. Same behavior (debounced
search, dropdown with name + email, loading/no-results states) but
using the established reusable component.

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

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

@@ -25,6 +25,7 @@ function storeLoyaltyTerminal() {
         selectedCard: null,
         searchResults: [],
         showSearchDropdown: false,
+        searchingCustomers: false,
         _searchTimeout: null,
 
         // Transaction inputs
@@ -161,6 +162,7 @@ function storeLoyaltyTerminal() {
         },
 
         async searchCustomers() {
+            this.searchingCustomers = true;
             try {
                 const params = new URLSearchParams({
                     search: this.searchQuery,
@@ -176,6 +178,8 @@ function storeLoyaltyTerminal() {
                 loyaltyTerminalLog.warn('Search failed:', error.message);
                 this.searchResults = [];
                 this.showSearchDropdown = false;
+            } finally {
+                this.searchingCustomers = false;
             }
         },