feat(helpdesk): ticket detail drawer — third drawer consumer

Migrates the ticket detail view (communication feed + ticket metadata aside)
into the core detail drawer pattern. Click a ticket number in the customer's
support tab → drawer slides in with the full ticket thread; arrow icons step
through the current filter page; ↗ opens the full page.

- `modules/helpdesk/templates/helpdesk-ticket-detail.phtml` extracts the
  body (communication feed container + metadata aside + i18n JSON) so the
  full page and the fragment render from the same source.
- `ticket-fragment($id).php` / `(none).phtml` reuse BcODataGateway::getTicket
  and enforce the same ABILITY_ACCESS guard as the full page. Connection
  errors render inline without aborting the fragment.
- Route `helpdesk/ticket-fragment/{id}` declared in module.php.
- `helpdesk-detail.js` wires the tickets grid: ticket-no formatter emits
  `data-drawer-trigger`, `linkColumn` disabled, `initDetailDrawer` called
  with `onContentLoaded → initHelpdeskTicket(contentEl)` so the async
  communication feed loads inside the drawer just like on the full page.
- `fetchUrl`/`fullUrl` written as single-expression arrows so the
  DetailDrawerFragmentContractTest can discover the consumer and validate
  the fragment endpoint files exist — the test now covers all three drawer
  consumers (address book, admin users, helpdesk tickets).

The full-page ticket view is unchanged for users who deep-link directly;
only the router-to-body wiring moved through the partial.

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

modules/helpdesk/web/js/helpdesk-detail.js

@@ -10,6 +10,8 @@ import { initListSection } from '/js/core/app-list-page-module.js';
 import { getJson } from '/js/core/app-http.js';
 import { resolveHost } from '/js/core/app-dom.js';
 import { readPageConfig } from '/js/core/app-page-config.js';
+import { initDetailDrawer } from '/js/components/app-detail-drawer.js';
+import { initHelpdeskTicket } from './helpdesk-ticket.js';
 import {
   renderCommunicationError,
   renderCommunicationFeed,
@@ -776,7 +778,7 @@ function init(container) {
           {
             name: labels.ticketNo || 'Ticket No.',
             sort: true,
-            formatter: (cell) => gridjs.html(`<a href="${cell.url}">${cell.no}</a>`),
+            formatter: (cell) => gridjs.html(`<a class="app-grid-link-cell" href="${cell.url}" data-drawer-trigger data-ticket-no="${cell.no || ''}">${cell.no}</a>`),
           },
           { name: labels.description || 'Description', sort: false },
           {
@@ -816,10 +818,13 @@ function init(container) {
             return url || '';
           },
         },
-        rowInteraction: { linkColumn: 0 },
+        rowInteraction: { linkColumn: false },
+        rowDataset: (row) => ({
+          uuid: row?.cells?.[0]?.data?.no || '',
+        }),
       };
 
-      initListSection({
+      const section = initListSection({
         moduleId: 'helpdesk-detail-tickets',
         initErrorMessage: 'Helpdesk tickets grid init failed',
         initOptions: {
@@ -832,6 +837,26 @@ function init(container) {
         },
       });
       ticketsGridInitialized = true;
+
+      initDetailDrawer({
+        gridConfig: section?.gridConfig || null,
+        triggerSelector: '[data-drawer-trigger][data-ticket-no]',
+        rowUuidAttr: 'uuid',
+        fetchUrl: (ticketNo) => new URL(`helpdesk/ticket-fragment/${encodeURIComponent(ticketNo)}?from=${encodeURIComponent(customerNo || '')}`, appBase).toString(),
+        fullUrl: (ticketNo) => new URL(`helpdesk/ticket/${encodeURIComponent(ticketNo)}?from=${encodeURIComponent(customerNo || '')}`, appBase).toString(),
+        hashPrefix: 'ticket',
+        onContentLoaded: (contentEl) => {
+          try { initHelpdeskTicket(contentEl); } catch (err) { console.warn('[helpdesk-detail] initHelpdeskTicket failed', err); }
+        },
+        labels: {
+          close: labels.drawerClose || 'Close',
+          previous: labels.drawerPrev || 'Previous',
+          next: labels.drawerNext || 'Next',
+          openFull: labels.drawerOpenFull || 'Open full page',
+          loading: labels.drawerLoading || 'Loading',
+          error: labels.drawerError || 'Failed to load',
+        },
+      });
     } finally {
       ticketsGridInitializing = false;
     }