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/components/form/FieldRenderer.vue

@@ -1,13 +1,14 @@
 <script setup lang="ts">
 import { computed } from 'vue'
-import { rendererFor, type FieldControlProps } from './registry'
+import { rendererForField, type FieldControlProps } from './registry'
 
-// Picks the control for field.type from the registry (D-05) and forwards the
+// Picks the control for the field from the registry (D-05; a plugin field
+// type's element host when the field names an element) and forwards the
 // shared control props and the value update.
 const props = defineProps<FieldControlProps>()
 const emit = defineEmits<{ 'update:modelValue': [value: unknown] }>()
 
-const control = computed(() => rendererFor(props.field.type))
+const control = computed(() => rendererForField(props.field))
 </script>
 
 <template>