fix(custom-fields) : context fields display, batch save, hierarchy propagation and UniqueEntity fix

- ComponentItem/PieceItem: DaisyUI divider, emit context-field-update for batch save
- CustomFieldDisplay: support editable/emit-blur/title/show-header props
- MachineComponentsCard/MachinePiecesCard: propagate custom-field-update events
- useMachineDetailCustomFields: pendingContextFieldUpdates + saveAllContextCustomFields
- useMachineDetailData: wire context field save into submitEdition
- useMachineDetailUpdates: only PATCH changed machine fields
- useMachineHierarchy: propagate contextCustomFields/Values from link to nodes
- componentStructure: include machineContextOnly in normalizeStructureForEditor
- Machine entity: convert empty reference to null, ignoreNull on UniqueEntity

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

frontend/app/components/PieceItem.vue

@@ -241,22 +241,27 @@
     <CustomFieldDisplay
       :fields="displayedCustomFields"
       :is-edit-mode="isEditMode"
+      title="Champs personnalisés item"
+      :editable="false"
       @field-input="handleCustomFieldInput"
       @field-blur="handleCustomFieldBlur"
     />
 
-        <!-- Context custom fields (machine-specific) -->
-        <div v-if="mergedContextFields.length" class="mt-4">
-          <h4 class="text-xs font-semibold text-base-content/70 mb-2">
-            Champs contextuels
-          </h4>
-          <CustomFieldDisplay
-            :fields="mergedContextFields"
-            :is-edit-mode="isEditMode"
-            :columns="2"
-            @field-blur="updateContextCustomField"
-          />
-        </div>
+    <template v-if="mergedContextFields.length">
+      <div class="divider my-4 text-xs text-base-content/50">
+        Champs personnalisés machine
+      </div>
+      <CustomFieldDisplay
+        :fields="mergedContextFields"
+        :is-edit-mode="isEditMode"
+        :columns="2"
+        :show-header="false"
+        :with-top-border="false"
+        :editable="true"
+        :emit-blur="false"
+        @field-input="queueContextCustomFieldUpdate"
+      />
+    </template>
 
     <div class="mt-4 pt-4 border-t border-base-200 space-y-3">
       <div class="flex items-center justify-between">
@@ -316,13 +321,14 @@ import {
 } from '~/shared/constructeurUtils'
 import {
   resolveFieldId,
-  resolveFieldReadOnly, mergeFieldDefinitionsWithValues, dedupeMergedFields 
+  resolveFieldReadOnly,
+  resolveCustomFieldId,
+  mergeFieldDefinitionsWithValues,
+  dedupeMergedFields,
 } from '~/shared/utils/entityCustomFieldLogic'
 import { useEntityDocuments } from '~/composables/useEntityDocuments'
 import { useEntityProductDisplay } from '~/composables/useEntityProductDisplay'
 import { useEntityCustomFields } from '~/composables/useEntityCustomFields'
-import { useCustomFields } from '~/composables/useCustomFields'
-import { useToast } from '~/composables/useToast'
 
 const props = defineProps({
   piece: { type: Object, required: true },
@@ -390,9 +396,6 @@ const {
   updateCustomField,
 } = useEntityCustomFields({ entity: () => props.piece, entityType: 'piece' })
 
-const { upsertCustomFieldValue } = useCustomFields()
-const { showSuccess, showError } = useToast()
-
 const mergedContextFields = computed(() => {
   const definitions = props.piece?.contextCustomFields ?? []
   const values = props.piece?.contextCustomFieldValues ?? []
@@ -402,26 +405,23 @@ const mergedContextFields = computed(() => {
   )
 })
 
-const updateContextCustomField = async (field) => {
+const queueContextCustomFieldUpdate = (field, value) => {
   const linkId = props.piece?.linkId
   if (!linkId || !field) return
 
-  const customFieldId = field.customFieldId || field.customField?.id
-  if (!customFieldId) return
+  const customFieldId = resolveCustomFieldId(field)
+  const customFieldValueId = resolveFieldId(field)
+  if (!customFieldId && !customFieldValueId) return
 
-  const result = await upsertCustomFieldValue(
-    customFieldId,
-    'machinePieceLink',
-    linkId,
-    field.value ?? '',
-  )
-
-  if (result.success) {
-    showSuccess(`Champ contextuel "${field.name || field.customField?.name}" mis à jour`)
-  }
-  else {
-    showError(`Erreur lors de la mise à jour du champ contextuel`)
-  }
+  field.value = value
+  emit('custom-field-update', {
+    entityType: 'machinePieceLink',
+    entityId: linkId,
+    fieldId: customFieldId,
+    customFieldValueId,
+    value: value ?? '',
+    fieldName: field.name || field.customField?.name || 'Champ contextuel',
+  })
 }
 
 // --- Document edit modal ---