Feat v0.6.1-v0.6.2: backup/restore, docs surface, dynamic OpenAPI

v0.6.1 — Backup tooling (.swb ZIP export/import), admin backup section,
docs surface with markdown rendering, 5 reference docs, 6 handler tests.

v0.6.2 — Dark mode contrast fixes, topbar nav, 📖 docs icon, dynamic
OpenAPI spec with extension route merging, docs outline sidebar,
scroll/routing fixes; 7 new tests.

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

src/js/sw/surfaces/admin/index.js

@@ -21,7 +21,7 @@ import { UserMenu } from '../../shell/user-menu.js';
 const ADMIN_SECTIONS = {
     people:     ['users', 'teams', 'groups'],
     workflows:  ['workflows'],
-    system:     ['settings', 'storage', 'packages', 'connections', 'broadcast'],
+    system:     ['settings', 'storage', 'packages', 'connections', 'broadcast', 'backup'],
     monitoring: ['audit'],
 };
 
@@ -30,6 +30,7 @@ const ADMIN_LABELS = {
     workflows: 'Workflows',
     settings: 'Settings', storage: 'Storage', packages: 'Packages',
     connections: 'Connections', broadcast: 'Broadcast',
+    backup: 'Backup',
     audit: 'Audit',
 };
 
@@ -67,6 +68,7 @@ const sectionModules = {
     packages:       () => import(`./packages.js${_v}`),
     connections:    () => import(`./connections.js${_v}`),
     broadcast:      () => import(`./broadcast.js${_v}`),
+    backup:         () => import(`./backup.js${_v}`),
     audit:          () => import(`./audit.js${_v}`),
 };