Add Archer Template Library for risk acceptance form reuse

Adds a template management system to the Ivanti Queue's Archer Risk
Acceptance workflow. Templates store static form content (Environment
Overview, Segmentation, Mitigating Controls, etc.) organized by
Vendor > Platform > Model hierarchy.

Features:
- Full CRUD API at /api/archer-templates with search, filter, clone,
  and hierarchy navigation endpoints
- Template Manager page (nav: Template Mgr) with grouped list view,
  create/edit/clone/delete modals, role-based access
- TemplateSelector component integrated into Ivanti Todo Queue for
  Archer workflow items with per-section copy-to-clipboard buttons
  and Copy All functionality
- Database migration with case-insensitive uniqueness enforcement
- Audit logging for all template mutations

New files:
- backend/migrations/add_archer_templates_table.js
- backend/routes/archerTemplates.js
- frontend/src/components/pages/ArcherTemplatePage.js
- frontend/src/components/TemplateSelector.js
- frontend/src/components/TemplateFormModal.js
- frontend/src/components/DeleteConfirmModal.js

frontend/src/App.js

@@ -19,6 +19,7 @@ import JiraPage from './components/pages/JiraPage';
 import AdminPage from './components/pages/AdminPage';
 import ArchiveSummaryBar from './components/pages/ArchiveSummaryBar';
 import ArcherPage from './components/pages/ArcherPage';
+import ArcherTemplatePage from './components/pages/ArcherTemplatePage';
 import FeedbackModal from './components/FeedbackModal';
 import NotificationBell from './components/NotificationBell';
 import './App.css';
@@ -199,7 +200,7 @@ export default function App() {
   const [cveDocuments, setCveDocuments] = useState({});
   const [quickCheckCVE, setQuickCheckCVE] = useState('');
   const [quickCheckResult, setQuickCheckResult] = useState(null);
-  const VALID_PAGES = new Set(['home', 'triage', 'compliance', 'knowledge-base', 'exports', 'jira', 'admin']);
+  const VALID_PAGES = new Set(['home', 'triage', 'compliance', 'knowledge-base', 'exports', 'jira', 'admin', 'archer-templates']);
   const [currentPage, setCurrentPageRaw] = useState(() => {
     try {
       const saved = localStorage.getItem('cve-dashboard-page');
@@ -1105,6 +1106,7 @@ export default function App() {
         {currentPage === 'knowledge-base' && <KnowledgeBasePage />}
         {currentPage === 'exports'        && <ExportsPage />}
         {currentPage === 'jira'           && <JiraPage />}
+        {currentPage === 'archer-templates' && <ArcherTemplatePage />}
         {currentPage === 'admin' && isAdmin() && <AdminPage />}
         {currentPage === 'admin' && !isAdmin() && (() => { setCurrentPage('home'); return null; })()}