feat(10-03): open, edit and save a record with toast and 422 feedback

- The SPA loads the backend::lang bundle before /auth/me, sets the
  document language from meta.locale and renders plural messages with
  Intl.PluralRules; interpolate mirrors phrasebook for :name/:Name/:NAME
- Create and record routes; mapWinterUrl maps recordUrl and redirects
  onto the controller's list, create and record routes only
- List rows open their record; FormView loads the form schema and the
  record, shows context-allowed fields in the span grid, saves values
  keyed by field name and toasts the resolved saved message
- A 422 puts each message under its field (aria-invalid,
  aria-describedby), shows the plural banner, focuses the first invalid
  field in schema order and clears a field's error on change
- The D-05 registry maps text, textarea, number and dropdown; any other
  type renders the unsupported-field box with the type in DM Mono
- The admin OpenAPI document declares the write request bodies
  (AdminRecord, AdminIDsRequest) and the list filter query as a
  deepObject, so the typed client can send them
- New backend::lang form.load_failed key; boardwalk/dist rebuilt

admin/src/components/form/fields/UnsupportedField.vue

@@ -0,0 +1,34 @@
+<script setup lang="ts">
+import { computed } from 'vue'
+import { Puzzle } from '@lucide/vue'
+import { t } from '../../../app/i18n'
+import type { FieldControlProps } from '../registry'
+
+// D-05 fallback for any field type without a renderer. The translated
+// sentence is split around the type so the type renders in DM Mono, as text.
+const props = defineProps<FieldControlProps>()
+
+const MARK = '\u0000'
+
+const parts = computed(() => {
+  const [before = '', after = ''] = t('backend::lang.form.unsupported_field', { type: MARK }).split(MARK)
+  return { before, after }
+})
+
+const hasType = computed(() => t('backend::lang.form.unsupported_field', { type: MARK }).includes(MARK))
+</script>
+
+<template>
+  <div
+    :id="controlId"
+    data-unsupported-field
+    :aria-describedby="describedBy || undefined"
+    class="flex min-h-input items-center gap-2.5 rounded-control border-[1.5px] border-dashed border-border-strong bg-subtle px-3.5 text-[13px] text-muted"
+  >
+    <Puzzle :size="16" aria-hidden="true" />
+    <span v-if="hasType"
+      >{{ parts.before }}<code class="font-mono text-text">{{ props.field.type }}</code>{{ parts.after }}</span
+    >
+    <span v-else>{{ t('backend::lang.form.unsupported_field') }} <code class="font-mono text-text">{{ props.field.type }}</code></span>
+  </div>
+</template>