feat(forms): add FormField wrapper + useFormError composable per RFC Appendix A

Two new artifacts that together provide the F4 form-migration target:

apps/app/src/components/forms/FormField.vue — project-owned wrapper
around @primevue/forms' built-in FormField. The default slot accepts
the actual input (e.g. <InputText name="email" />); the wrapper renders
label (with optional required asterisk), error Message, and hint chrome
around it. Reads field state from the parent <Form> via the built-in
FormField's scoped slot, so call-sites do not need to thread $form
manually.

apps/app/src/composables/useFormError.ts — the API 422 bridge. Parent
component calls useFormError() once; the composable provides an
apiErrors ref through Vue inject. Each FormField in the component
reads its own field name from that map. applyApiErrors() reads the
Crewli backend's { errors: { field: string[] } } shape and surfaces
the first message per field; clearApiErrors() resets between submits.

Error precedence per RFC Appendix A: explicit apiError prop > inject
apiErrors map > Zod resolver error from $field.

Signature note: RFC's useFormError(formRef) is implemented as
useFormError() — the formRef parameter is unused in the provide/inject
implementation, and Crewli convention avoids unused parameters. RFC
will be aligned in B9 if it remains a meaningful spec gap during F4.

Verification:
- pnpm typecheck — clean.
- pnpm test — 402 tests pass unchanged.
- B8 will exercise the components end-to-end on the login page; F4d
  validates against the public-registration multi-step form.

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

apps/app/src/components/forms/FormField.vue

@@ -0,0 +1,93 @@
+<script setup lang="ts">
+// Crewli FormField wrapper — terse call-site syntax that hides the
+// @primevue/forms validation plumbing. Per RFC Appendix A.
+//
+// Usage:
+//   <Form :resolver="zodResolver(schema)" @submit="onSubmit">
+//     <FormField name="email" label="E-mailadres" required>
+//       <InputText name="email" />
+//     </FormField>
+//   </Form>
+//
+// The default slot accepts any PrimeVue input whose `name` matches the
+// FormField's `name` prop. The parent <Form> auto-registers each named
+// input. This wrapper renders the surrounding label, error message,
+// and hint, reading the field state from the parent Form context via
+// @primevue/forms' built-in <FormField> scoped slot.
+//
+// Error precedence: apiError prop > useFormError() provide/inject map >
+// Zod resolver error. The first non-empty source wins.
+
+import { type Ref, computed, inject } from 'vue'
+import { FormField as PrimeFormField } from '@primevue/forms'
+import Message from 'primevue/message'
+import {
+  FORM_API_ERRORS_KEY,
+  type FormApiErrorsMap,
+} from '@/composables/useFormError'
+
+interface Props {
+  name: string
+  label?: string
+  required?: boolean
+  hint?: string
+  apiError?: string | null
+}
+
+const props = withDefaults(defineProps<Props>(), {
+  label: undefined,
+  required: false,
+  hint: undefined,
+  apiError: null,
+})
+
+const injectedApiErrors = inject<Ref<FormApiErrorsMap> | null>(
+  FORM_API_ERRORS_KEY,
+  null,
+)
+
+const resolvedApiError = computed<string | null>(() => {
+  if (props.apiError)
+    return props.apiError
+
+  return injectedApiErrors?.value[props.name] ?? null
+})
+</script>
+
+<template>
+  <PrimeFormField
+    v-slot="$field"
+    :name="name"
+  >
+    <div class="crewli-field mb-4 flex flex-col gap-1">
+      <label
+        v-if="label"
+        :for="name"
+        class="text-sm font-medium"
+      >
+        {{ label }}
+        <span
+          v-if="required"
+          aria-label="verplicht"
+          class="text-red-500"
+        >*</span>
+      </label>
+
+      <slot />
+
+      <Message
+        v-if="resolvedApiError || ($field?.invalid && $field?.error)"
+        severity="error"
+        size="small"
+        variant="simple"
+      >
+        {{ resolvedApiError ?? $field.error?.message ?? $field.errors?.[0]?.message }}
+      </Message>
+
+      <small
+        v-else-if="hint"
+        class="text-surface-500"
+      >{{ hint }}</small>
+    </div>
+  </PrimeFormField>
+</template>

apps/app/src/composables/useFormError.ts

@@ -0,0 +1,44 @@
+// useFormError — merges Laravel 422 validation responses into the
+// surrounding Form's per-field error display.
+//
+// Pattern: a parent component calls useFormError() once. The composable
+// provides an apiErrors map via Vue inject. Each FormField inside the
+// component reads its own field name from that map and falls through to
+// its $field.error (the Zod resolver result) when no API error is set.
+// apiError precedence > Zod error per RFC Appendix A.
+//
+// Crewli backend 422 shape: { message, errors: { field: string[] } }.
+// We surface the first message per field.
+
+import { type Ref, provide, ref } from 'vue'
+
+export const FORM_API_ERRORS_KEY = Symbol('crewli-form-api-errors')
+
+export type FormApiErrorsMap = Record<string, string>
+
+export interface UseFormErrorReturn {
+  applyApiErrors: (errors: Record<string, string[]>) => void
+  clearApiErrors: () => void
+  apiErrors: Ref<FormApiErrorsMap>
+}
+
+export function useFormError(): UseFormErrorReturn {
+  const apiErrors = ref<FormApiErrorsMap>({})
+
+  provide(FORM_API_ERRORS_KEY, apiErrors)
+
+  function applyApiErrors(errors: Record<string, string[]>): void {
+    const next: FormApiErrorsMap = {}
+    for (const [field, messages] of Object.entries(errors)) {
+      if (Array.isArray(messages) && messages.length > 0)
+        next[field] = messages[0]
+    }
+    apiErrors.value = next
+  }
+
+  function clearApiErrors(): void {
+    apiErrors.value = {}
+  }
+
+  return { applyApiErrors, clearApiErrors, apiErrors }
+}