feat(16.2-01): host plugin field type elements in the admin SPA

- loadFieldTypes fetches GET /field-types after sign-in, loads each script
  once and adds the styles as global links activateStyles never disables
- PluginField creates the type's element, sets the value property and the
  contract attributes, takes summer-change as the form value and never
  writes back a value the element just emitted
- rendererForField and isRegisteredField route any field with an element
  to PluginField in forms, previews and the save payload
- rebuilt modules/boardwalk/dist

admin/src/views/LoginView.vue

@@ -2,6 +2,7 @@
 import { ref } from 'vue'
 import { useRoute, useRouter } from 'vue-router'
 import { CircleAlert, Sun } from '@lucide/vue'
+import { loadFieldTypes } from '../app/fieldTypes'
 import { t } from '../app/i18n'
 import { safeRedirect } from '../app/router'
 import { login, me } from '../state/useAuth'
@@ -29,7 +30,7 @@ async function submit(): Promise<void> {
       return
     }
     password.value = ''
-    await Promise.all([loadNavigation(), loadSettings().catch(() => [])])
+    await Promise.all([loadNavigation(), loadSettings().catch(() => []), loadFieldTypes()])
     await router.replace(safeRedirect(route.query.redirect) ?? '/')
   } finally {
     busy.value = false