refactor(custom-fields) : unify 3 parallel implementations into 1 module

Replace ~2900 lines across 9 files with ~400 lines in 2 files:
- shared/utils/customFields.ts (types + pure helpers)
- composables/useCustomFieldInputs.ts (reactive composable)

Migrated all consumers:
- Backend: add defaultValue to API Platform serialization groups
- Standalone pages: component edit/create, piece edit/create, product edit/create/detail
- Machine page: MachineCustomFieldsCard, MachineInfoCard, useMachineDetailCustomFields
- Hierarchy: ComponentItem, PieceItem
- Shared: CustomFieldDisplay, CustomFieldInputGrid
- Category editor: componentStructure.ts

Deleted:
- entityCustomFieldLogic.ts (335 lines)
- customFieldUtils.ts (440 lines)
- customFieldFormUtils.ts (404 lines)
- useEntityCustomFields.ts (181 lines)
- customFieldFormUtils.test.ts

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/app/composables/usePieceEdit.ts

@@ -2,7 +2,6 @@ import { computed, onMounted, reactive, ref, watch } from 'vue'
 import { useRouter } from '#imports'
 import { usePieceTypes } from '~/composables/usePieceTypes'
 import { usePieces } from '~/composables/usePieces'
-import { useCustomFields } from '~/composables/useCustomFields'
 import { useApi } from '~/composables/useApi'
 import { useToast } from '~/composables/useToast'
 import { useDocuments } from '~/composables/useDocuments'
@@ -26,12 +25,7 @@ import {
   collectNormalizedProductIds,
 } from '~/shared/utils/pieceProductSelectionUtils'
 import { getModelType } from '~/services/modelTypes'
-import {
-  type CustomFieldInput,
-  buildCustomFieldInputs,
-  requiredCustomFieldsFilled as _requiredCustomFieldsFilled,
-  saveCustomFieldValues as _saveCustomFieldValues,
-} from '~/shared/utils/customFieldFormUtils'
+import { useCustomFieldInputs, type CustomFieldInput } from '~/composables/useCustomFieldInputs'
 
 interface PieceCatalogType extends ModelType {
   structure: PieceModelStructure | null
@@ -44,7 +38,6 @@ export function usePieceEdit(pieceId: string) {
   const { get } = useApi()
   const { pieceTypes, loadPieceTypes } = usePieceTypes()
   const { updatePiece } = usePieces()
-  const { upsertCustomFieldValue, updateCustomFieldValue } = useCustomFields()
   const toast = useToast()
   const { loadDocumentsByPiece, uploadDocuments, deleteDocument } = useDocuments()
   const { ensureConstructeurs } = useConstructeurs()
@@ -90,19 +83,26 @@ export function usePieceEdit(pieceId: string) {
   const constructeurIdsFromForm = computed(() => constructeurIdsFromLinks(constructeurLinks.value))
   const productSelections = ref<(string | null)[]>([])
 
-  const customFieldInputs = ref<CustomFieldInput[]>([])
   const resolvedStructure = computed<PieceModelStructure | null>(() =>
     pieceTypeDetails.value?.structure ?? selectedType.value?.structure ?? null,
   )
 
-  const refreshCustomFieldInputs = (
-    structureOverride?: PieceModelStructure | null,
-    valuesOverride?: any[] | null,
-  ) => {
-    const structure = structureOverride ?? resolvedStructure.value ?? null
-    const values = valuesOverride ?? piece.value?.customFieldValues ?? null
-    customFieldInputs.value = buildCustomFieldInputs(structure, values)
-  }
+  const {
+    fields: customFieldInputs,
+    requiredFilled: requiredCustomFieldsFilled,
+    saveAll: saveAllCustomFields,
+    refresh: refreshCustomFieldInputs,
+  } = useCustomFieldInputs({
+    definitions: computed(() => resolvedStructure.value?.customFields ?? []),
+    values: computed(() => piece.value?.customFieldValues ?? []),
+    entityType: 'piece',
+    entityId: computed(() => piece.value?.id ?? null),
+    onValueCreated: (newValue) => {
+      if (piece.value && Array.isArray(piece.value.customFieldValues)) {
+        piece.value.customFieldValues.push(newValue)
+      }
+    },
+  })
 
   const openPreview = (doc: any) => {
     if (!doc || !canPreviewDocument(doc)) {
@@ -221,10 +221,6 @@ export function usePieceEdit(pieceId: string) {
     pendingProductIds = []
   })
 
-  const requiredCustomFieldsFilled = computed(() =>
-    _requiredCustomFieldsFilled(customFieldInputs.value),
-  )
-
   const canSubmit = computed(() =>
     Boolean(
       canEdit.value
@@ -247,9 +243,7 @@ export function usePieceEdit(pieceId: string) {
       piece.value = result.data
       pieceDocuments.value = Array.isArray(result.data?.documents) ? result.data.documents : []
 
-      // Use customFieldValues from entity response (enriched with customField definitions via serialization groups)
-      const customValues = Array.isArray(result.data?.customFieldValues) ? result.data.customFieldValues : []
-      refreshCustomFieldInputs(undefined, customValues)
+      // The watcher on useCustomFieldInputs will auto-refresh when piece.value changes
 
       // Use cached type from loadPieceTypes() instead of separate getModelType() call
       loadPieceTypeDetailsFromCache(result.data)
@@ -275,14 +269,14 @@ export function usePieceEdit(pieceId: string) {
     const cachedType = (pieceTypes.value || []).find((t: any) => t.id === typeId) ?? null
     if (cachedType) {
       pieceTypeDetails.value = cachedType
-      refreshCustomFieldInputs((cachedType.structure as PieceModelStructure | null) ?? null, currentPiece?.customFieldValues ?? null)
+      // useCustomFieldInputs auto-refreshes via its watcher on resolvedStructure
       return
     }
     // Fallback: fetch if not in cache (edge case)
     getModelType(typeId).then((type) => {
       if (type && typeof type === 'object') {
         pieceTypeDetails.value = type
-        refreshCustomFieldInputs((type.structure as PieceModelStructure | null) ?? null, currentPiece?.customFieldValues ?? null)
+        // useCustomFieldInputs auto-refreshes via its watcher on resolvedStructure
       }
     }).catch(() => {
       pieceTypeDetails.value = null
@@ -336,29 +330,21 @@ export function usePieceEdit(pieceId: string) {
         pendingProductIds = []
       }
 
-      // After setting selectedTypeId, read selectedType.value (now updated) instead of
-      // the stale destructured currentType which was captured before the ID change.
-      const resolvedType = selectedType.value ?? pieceTypeDetails.value ?? null
-      refreshCustomFieldInputs(resolvedType?.structure ?? null, currentPiece.customFieldValues)
+      // useCustomFieldInputs auto-refreshes via its watcher on definitions + values
 
       initialized = true
     },
     { immediate: true },
   )
 
-  watch(selectedType, (currentType) => {
-    if (!piece.value || !currentType) {
-      return
-    }
-    refreshCustomFieldInputs(currentType.structure, piece.value.customFieldValues)
-  })
+  // useCustomFieldInputs auto-refreshes when selectedType changes (via resolvedStructure)
 
-  watch(resolvedStructure, (currentStructure) => {
+  watch(resolvedStructure, () => {
     if (!piece.value) {
       return
     }
     ensureProductSelections(structureProducts.value.length)
-    refreshCustomFieldInputs(currentStructure, piece.value.customFieldValues)
+    // useCustomFieldInputs auto-refreshes via its watcher on definitions
   })
 
   const submitEdition = async () => {
@@ -407,15 +393,10 @@ export function usePieceEdit(pieceId: string) {
     try {
       const result = await updatePiece(piece.value.id, payload)
       if (result.success && result.data) {
-        const updatedPiece = result.data as Record<string, any>
-        await _saveCustomFieldValues(
-          'piece',
-          updatedPiece.id,
-          [
-            updatedPiece?.typePiece?.structure?.customFields,
-          ],
-          { customFieldInputs, upsertCustomFieldValue, updateCustomFieldValue, toast },
-        )
+        const failedFields = await saveAllCustomFields()
+        if (failedFields.length) {
+          toast.showError(`Erreur sur les champs : ${failedFields.join(', ')}`)
+        }
         await syncLinks('piece', piece.value.id, originalConstructeurLinks.value, constructeurLinks.value)
         originalConstructeurLinks.value = constructeurLinks.value.map(l => ({ ...l }))
         toast.showSuccess('Pièce mise à jour avec succès.')