feat(helpdesk): add Domains list page with BC OData contract type enrichment

Add a new "Domains" page to the helpdesk module that fetches domain data
from the FS_Contract_Domains OData endpoint and enriches each domain with
its contract type (PI_Header_Type) by joining with FS_Contract_Lines_Test
where Type = 'Domain'.

New files:
- domains/index().php, index(default).phtml, filter-schema.php — list page
- domains-data().php — data endpoint with PHP-side filtering/sorting
- helpdesk-domains-index.js — Grid.js via initStandardListPage()

Gateway additions:
- listDomains() — fetch all contract domains
- listDomainContractLines() — fetch domain-type contract lines for type lookup

Sidebar restructured into three collapsible groups (Lookup, Monitoring,
Administration) with per-group icons and color coding, matching the core
admin panel pattern.

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

modules/helpdesk/web/js/pages/helpdesk-domains-index.js

@@ -0,0 +1,85 @@
+import { initStandardListPage } from '/js/core/app-grid-factory.js';
+import { readPageConfig } from '/js/core/app-page-config.js';
+import { warnOnce } from '/js/core/app-dom.js';
+import { escapeHtml, getAppBase, withCurrentListReturn } from '/js/pages/app-list-utils.js';
+
+const config = readPageConfig('helpdesk-domains');
+if (config) {
+  const gridjs = window.gridjs;
+  if (!gridjs) {
+    warnOnce('UI_INIT_FAIL', 'Helpdesk domains grid init failed: Grid.js missing', { module: 'helpdesk-domains', component: 'grid' });
+  } else {
+    const appBase = getAppBase();
+    const labels = config.labels || {};
+
+    const debitorUrlIndex = 6;
+
+    const gridOptions = {
+      gridjs,
+      container: '#helpdesk-domains-grid',
+      dataUrl: config.dataUrl || 'helpdesk/domains-data',
+      appBase,
+      columns: [
+        { name: labels.no || 'No.', sort: true },
+        {
+          name: labels.customerName || 'Customer Name',
+          sort: true,
+          formatter: (cell) => {
+            const name = escapeHtml(cell?.name || '');
+            const detailUrl = String(cell?.url || '').trim();
+            if (detailUrl === '') {
+              return gridjs.html(name);
+            }
+            const href = escapeHtml(withCurrentListReturn(detailUrl));
+            return gridjs.html(`<a href="${href}">${name}</a>`);
+          },
+        },
+        { name: labels.url || 'URL', sort: true },
+        { name: labels.contractType || 'Contract Type', sort: true },
+        {
+          name: labels.state || 'State',
+          sort: true,
+          formatter: (cell) => {
+            const state = escapeHtml(cell?.state || '');
+            const variant = cell?.variant || 'neutral';
+            return gridjs.html(`<span class="badge" data-variant="${escapeHtml(variant)}">${state}</span>`);
+          },
+        },
+        { name: labels.administration || 'Administration', sort: true },
+        { name: 'debitor_url', hidden: true },
+      ],
+      sortColumns: ['No', 'Customer_Name', 'URL', 'contract_type', 'State', 'Administration', null],
+      paginationLimit: 10,
+      language: config.gridLang || {},
+      mapData: (data) => (data.data || []).map((row) => [
+        row.No || '',
+        { name: row.Customer_Name || '', url: row.debitor_url || '' },
+        row.URL || '',
+        row.contract_type || '',
+        { state: row.State || '', variant: row.state_variant || 'neutral' },
+        row.Administration || '',
+        row.debitor_url || '',
+      ]),
+      search: config.gridSearch || null,
+      filterSchema: config.filterSchema || [],
+      urlSync: true,
+      rowInteraction: { linkColumn: 1 },
+      rowDblClick: {
+        getUrl: (rowData) => rowData?.cells?.[debitorUrlIndex]?.data || '',
+      },
+    };
+
+    const { gridConfig } = initStandardListPage({
+      grid: gridOptions,
+      filters: {
+        mode: 'drawer',
+        chipMeta: config.filterChipMeta || {},
+        watchInputs: ['#helpdesk-domains-search-input'],
+      },
+    });
+
+    if (!gridConfig || !gridConfig.grid) {
+      warnOnce('UI_INIT_FAIL', 'Helpdesk domains grid init failed', { module: 'helpdesk-domains', component: 'grid' });
+    }
+  }
+}