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/composables/useMachineDetailData.ts

@@ -151,13 +151,18 @@ export function useMachineDetailData(machineId: string) {
   const {
     machineCustomFields,
     visibleMachineCustomFields,
+    pendingContextFieldUpdates,
     transformCustomFields,
     transformComponentCustomFields,
     syncMachineCustomFields,
     setMachineCustomFieldValue,
     updateMachineCustomField,
     updatePieceCustomField,
+    handleCustomFieldUpdate,
+    queueContextFieldUpdate,
+    clearPendingContextFieldUpdates,
     saveAllMachineCustomFields,
+    saveAllContextCustomFields,
   } = useMachineDetailCustomFields({
     machine,
     isEditMode,
@@ -333,10 +338,13 @@ export function useMachineDetailData(machineId: string) {
       // 2. Save all custom field values
       await saveAllMachineCustomFields()
 
-      // 3. Reload machine data to get fresh state
+      // 3. Save contextual custom field values queued from piece/component inputs
+      await saveAllContextCustomFields()
+
+      // 4. Reload machine data to get fresh state
       await loadMachineData()
 
-      // 4. Exit edit mode
+      // 5. Exit edit mode
       isEditMode.value = false
       toast.showSuccess('Machine mise à jour avec succès')
     } catch (error) {
@@ -350,6 +358,7 @@ export function useMachineDetailData(machineId: string) {
   const cancelEdition = () => {
     initMachineFields()
     syncMachineCustomFields()
+    clearPendingContextFieldUpdates()
     constructeurLinks.value = originalConstructeurLinks.value.map(l => ({ ...l }))
     machineConstructeurIds.value = constructeurIdsFromLinks(constructeurLinks.value)
     isEditMode.value = false
@@ -486,7 +495,7 @@ export function useMachineDetailData(machineId: string) {
 
     // UI state
     machineDocumentFiles, machineDocumentsUploading, machineDocumentsLoaded,
-    machineCustomFields, previewDocument, previewVisible,
+    machineCustomFields, pendingContextFieldUpdates, previewDocument, previewVisible,
     isEditMode, debug,
     componentsCollapsed, collapseToggleToken, piecesCollapsed, pieceCollapseToggleToken,
 
@@ -499,7 +508,8 @@ export function useMachineDetailData(machineId: string) {
     findProductById, resolveProductReference, getProductDisplay,
     initMachineFields, getMachineFieldId,
     syncMachineCustomFields, setMachineCustomFieldValue,
-    updateMachineCustomField, updatePieceCustomField,
+    updateMachineCustomField, updatePieceCustomField, handleCustomFieldUpdate,
+    queueContextFieldUpdate, clearPendingContextFieldUpdates, saveAllContextCustomFields,
     refreshMachineDocuments, handleMachineFilesAdded, removeMachineDocument,
     openPreview, closePreview,
     updateMachineInfo, updateComponent, updatePieceFromComponent,