feat(portal): implement TAG_PICKER, AVAILABILITY_PICKER, SECTION_PRIORITY field types

- FieldTagPicker: VAutocomplete multiple with grouped category slots,
  empty/null category normalised to "Overig", empty-state info alert
  when the server delivers no tags.
- FieldAvailabilityPicker: date-grouped checkbox list, festival-aware
  via usePublicFormTimeSlots. Event-name subheaders only surface when
  the time-slots span multiple events. Time format strips seconds.
- FieldSectionPriority: tap-to-rank + drag-to-reorder via vuedraggable
  for desktop; mobile tap-only. Renumbers priorities on every mutation.
  Self-heals malformed modelValue. UI soft cap via
  validation_rules.max_priorities clamped to the backend hard cap of 5.
- FieldRenderer: three new types removed from isStubbed.
- publicFormInjection: page-level provide/inject for the public token.
- IdentityMatchBanner: prefers backend-provided Dutch copy with
  frontend defaults as defensive fallback.
- FormConfirmation wires the banner inline.
- usePublicFormTimeSlots and usePublicFormSections TanStack composables.
- 40 new Vitest assertions.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/portal/src/composables/api/usePublicFormSections.ts

@@ -0,0 +1,27 @@
+import { useQuery } from '@tanstack/vue-query'
+import type { Ref } from 'vue'
+import { apiClient } from '@/lib/axios'
+import type { PublicFormSectionOption } from '@/types/formBuilder'
+
+interface ApiResponse<T> {
+  data: T
+}
+
+// Sibling endpoint for SECTION_PRIORITY — festival-aware and dedup-by-name
+// per PublicFormController::sections (show_in_registration=true, standard).
+export function usePublicFormSections(token: Ref<string>) {
+  return useQuery({
+    queryKey: ['public-form', token, 'sections'],
+    queryFn: async (): Promise<PublicFormSectionOption[]> => {
+      const t = token.value
+      if (!t) throw new Error('Missing public_token')
+      const { data } = await apiClient.get<ApiResponse<PublicFormSectionOption[]>>(
+        `/public/forms/${t}/sections`,
+      )
+
+      return data.data
+    },
+    enabled: computed(() => !!token.value),
+    staleTime: 1000 * 60 * 5,
+  })
+}

apps/portal/src/composables/api/usePublicFormTimeSlots.ts

@@ -0,0 +1,28 @@
+import { useQuery } from '@tanstack/vue-query'
+import type { Ref } from 'vue'
+import { apiClient } from '@/lib/axios'
+import type { PublicFormTimeSlot } from '@/types/formBuilder'
+
+interface ApiResponse<T> {
+  data: T
+}
+
+// Sibling endpoint for AVAILABILITY_PICKER — festival-aware per
+// PublicFormController::timeSlots (parent + children, VOLUNTEER only).
+// Cached for 5 minutes; data is effectively static during a session.
+export function usePublicFormTimeSlots(token: Ref<string>) {
+  return useQuery({
+    queryKey: ['public-form', token, 'time-slots'],
+    queryFn: async (): Promise<PublicFormTimeSlot[]> => {
+      const t = token.value
+      if (!t) throw new Error('Missing public_token')
+      const { data } = await apiClient.get<ApiResponse<PublicFormTimeSlot[]>>(
+        `/public/forms/${t}/time-slots`,
+      )
+
+      return data.data
+    },
+    enabled: computed(() => !!token.value),
+    staleTime: 1000 * 60 * 5,
+  })
+}

apps/portal/src/composables/publicFormInjection.ts

@@ -0,0 +1,21 @@
+import type { InjectionKey, Ref } from 'vue'
+import { inject, provide } from 'vue'
+
+// Page-level provide/inject for the public form token. Sibling-endpoint
+// fetches (time-slots, sections) read it instead of receiving it as a
+// prop through FieldRenderer, which would couple every renderer to every
+// new sibling resource.
+export const PUBLIC_FORM_TOKEN_KEY: InjectionKey<Ref<string>> = Symbol('PublicFormToken')
+
+export function providePublicFormToken(token: Ref<string>): void {
+  provide(PUBLIC_FORM_TOKEN_KEY, token)
+}
+
+export function usePublicFormToken(): Ref<string> {
+  const token = inject(PUBLIC_FORM_TOKEN_KEY)
+  if (!token) {
+    throw new Error('usePublicFormToken: no token provided. Did you forget providePublicFormToken in the page?')
+  }
+
+  return token
+}