feat(cabana): read-only Plugins screen with installed plugins

- GET /plugins (backend.view_plugins, superusers always pass) lists the
  plugins from party.Installed, or party.Activated IDs for older builds,
  with the built framework version and whether the registry is configured
- Settings -> System -> Plugins entry with the new SettingsEntry.path,
  added only for principals allowed to open it
- PluginsView at /system/plugins with an Installed tab (reka-ui Tabs);
  settings panel, rail, breadcrumbs and page title know the route
- OpenAPI and SPA types regenerated; contract, token-class and
  conformance inventories list the route; en/pl strings; docs

admin/src/components/shell/AppShell.vue

@@ -11,7 +11,7 @@ import ShortcutHelpDialog from './ShortcutHelpDialog.vue'
 import { ExternalLink } from '@lucide/vue'
 import { controllerIdFromPath } from '../../app/controllerRoutes'
 import { activeEntry } from '../../state/useNavigation'
-import { settingsEntry, settingsLinkFor, settingsSectionOf } from '../../state/useSettings'
+import { settingsEntry, settingsEntryForPath, settingsLinkFor, settingsSectionOf } from '../../state/useSettings'
 import { useSidebar } from '../../state/useSidebar'
 import { t } from '../../app/i18n'
 import { closeShortcutHelp, installHotkeys } from '../../app/hotkeys'
@@ -52,6 +52,9 @@ const settingsSection = computed(() => {
   if (route.name === 'settings-form') {
     return settingsSectionOf(settingsEntry(String(route.params.code ?? '')))
   }
+  if (route.name === 'plugins') {
+    return settingsSectionOf(settingsEntryForPath(route.path))
+  }
   return settingsSectionOf(settingsLinkFor(controllerIdFromPath(route.path)))
 })
 

admin/src/components/shell/Breadcrumbs.vue

@@ -25,6 +25,9 @@ const crumbs = computed<Crumb[]>(() => {
   if (route.name === 'account') {
     return [{ label: t('backend::lang.myaccount.menu_label') }]
   }
+  if (route.name === 'plugins') {
+    return [{ label: t('backend::lang.nav.settings'), to: '/settings' }, { label: t('backend::lang.plugins.title') }]
+  }
   if (route.name === 'settings' || route.name === 'settings-form') {
     const out: Crumb[] = [{ label: t('backend::lang.nav.settings'), to: '/settings' }]
     const entry = route.name === 'settings-form' ? settingsEntry(String(route.params.code ?? '')) : null

admin/src/components/shell/PluginRail.vue

@@ -7,7 +7,7 @@ import { controllerIdFromPath } from '../../app/controllerRoutes'
 import { iconFor } from '../../app/icons'
 import { activeEntry, firstControllerPath, railEntries } from '../../state/useNavigation'
 import { cycleTheme, themeChoice } from '../../state/usePreferences'
-import { hasSettings, settingsLinkFor } from '../../state/useSettings'
+import { hasSettings, settingsEntryForPath, settingsLinkFor } from '../../state/useSettings'
 import { useSidebar } from '../../state/useSidebar'
 import SectionFlyout from './SectionFlyout.vue'
 
@@ -45,6 +45,7 @@ const inSettings = computed(
   () =>
     route.path === '/settings' ||
     route.path.startsWith('/settings/') ||
+    settingsEntryForPath(route.path) !== null ||
     (active.value === null && settingsLinkFor(controllerIdFromPath(route.path)) !== null),
 )