refactor(admin/users): migrate CSV export to core primitive

Replace the inline export implementation with the new generic primitive
(core/Service/Export + helpers/export + app-list-export.js). No more
hand-rolled fputcsv loop, header setup, or escape closure duplicated
here — one implementation, tested once, reused everywhere.

- export().php: uses exportRequireGetRequest, exportCapLimit,
  exportResolveFlavor, ExportColumn[], exportSendCsv. Phone/mobile/
  short_dial keep allowSignedNumeric=true so +49 numbers render
  untouched.
- export(none).phtml: deleted — headers + fputcsv now live in the
  core helper.
- index(default).phtml: inline <details class="dropdown"> "Export CSV"
  replaced by the reusable app-list-export-dropdown partial, exposing
  CSV and Excel flavors. exportUrl added to pageConfig.
- app-users-list.js: hand-rolled export-button binding removed in
  favor of initListExport({ gridConfig, exportUrl }).
- admin-users-index.js: forwards config.exportUrl into
  initUsersListPage.

Net effect: ~100 lines of duplicated export plumbing removed from the
users page; users gain the Excel flavor for free.

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

web/js/pages/admin-users-index.js

@@ -171,6 +171,7 @@ createListPageModule({
       appBase,
       csrf,
       labels,
+      exportUrl: config.exportUrl,
       buildBulkUrl,
       bulkDownloadForms: {
         'access-pdf': '#users-access-pdf-bulk-form',

web/js/pages/app-users-list.js

@@ -1,6 +1,7 @@
 import { confirmDialog } from '../core/app-confirm-dialog.js';
 import { warnOnce } from '../core/app-dom.js';
 import { postForm } from '../core/app-http.js';
+import { initListExport } from '../core/app-list-export.js';
 
 export function initUsersListPage(options = {}) {
   const {
@@ -10,7 +11,7 @@ export function initUsersListPage(options = {}) {
     labels = {},
     selectors = {},
     bulkDownloadForms = {},
-    exportPath = 'admin/users/export',
+    exportUrl,
     listPath = 'admin/users',
     resetOptions = {},
     buildBulkUrl,
@@ -20,7 +21,6 @@ export function initUsersListPage(options = {}) {
 
   if (!gridConfig) {return;}
 
-  const exportSelector = selectors.exportButton || '[data-users-export]';
   const resetSelector = selectors.resetButton || '[data-users-reset]';
   const bulkSelector = selectors.bulkButtons || '[data-users-bulk]';
 
@@ -33,19 +33,8 @@ export function initUsersListPage(options = {}) {
     return postForm(url, body);
   };
 
-  const exportButton = document.querySelector(exportSelector);
-  if (exportButton) {
-    exportButton.addEventListener('click', () => {
-      const exportUrl = new URL(exportPath, appBase);
-      const dataUrl = new URL(gridConfig.baseUrl());
-      dataUrl.searchParams.forEach((value, key) => exportUrl.searchParams.set(key, value));
-      const sortParams = gridConfig.getSortParams ? gridConfig.getSortParams() : null;
-      if (sortParams && sortParams.order) {
-        exportUrl.searchParams.set('order', sortParams.order);
-        exportUrl.searchParams.set('dir', sortParams.dir || 'asc');
-      }
-      window.location.href = exportUrl.toString();
-    });
+  if (exportUrl) {
+    initListExport({ gridConfig, exportUrl });
   }
 
   const resetButton = document.querySelector(resetSelector);