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/common/CustomFieldDisplay.vue

@@ -1,10 +1,10 @@
 <template>
   <div
     v-if="fields.length"
-    class="mt-4 pt-4 border-t border-base-200"
+    :class="containerClass"
   >
-    <h5 class="text-sm font-medium text-base-content/80 mb-3">
-      Champs personnalisés
+    <h5 v-if="showHeader" class="text-sm font-medium text-base-content/80 mb-3">
+      {{ title }}
     </h5>
     <div :class="layoutClass">
       <div
@@ -23,7 +23,7 @@
         </label>
 
         <!-- Mode édition -->
-        <template v-if="isEditMode && !resolveFieldReadOnly(field)">
+        <template v-if="isFieldEditable(field)">
           <!-- Champ de type TEXT -->
           <input
             v-if="resolveFieldType(field) === 'text'"
@@ -142,6 +142,11 @@ const props = defineProps<{
   fields: any[]
   isEditMode: boolean
   columns?: 1 | 2
+  title?: string
+  showHeader?: boolean
+  withTopBorder?: boolean
+  editable?: boolean
+  emitBlur?: boolean
 }>()
 
 const emit = defineEmits<{
@@ -155,6 +160,20 @@ const layoutClass = computed(() =>
     : 'space-y-3',
 )
 
+const title = computed(() => props.title ?? 'Champs personnalisés')
+const showHeader = computed(() => props.showHeader ?? true)
+const containerClass = computed(() =>
+  props.withTopBorder === false
+    ? ''
+    : 'mt-4 pt-4 border-t border-base-200',
+)
+const editable = computed(() => props.editable ?? true)
+const emitBlur = computed(() => props.emitBlur ?? true)
+
+function isFieldEditable(field: any) {
+  return props.isEditMode && editable.value && !resolveFieldReadOnly(field)
+}
+
 function onInput(field: any, value: string) {
   field.value = value
   emit('field-input', field, value)
@@ -164,10 +183,14 @@ function onBooleanChange(field: any, checked: boolean) {
   const value = checked ? 'true' : 'false'
   field.value = value
   emit('field-input', field, value)
-  emit('field-blur', field)
+  if (emitBlur.value) {
+    emit('field-blur', field)
+  }
 }
 
 function onBlur(field: any) {
-  emit('field-blur', field)
+  if (emitBlur.value) {
+    emit('field-blur', field)
+  }
 }
 </script>