refactor(frontend) : extract shared components and reduce file sizes

- Extract CustomFieldInputGrid.vue from 6 duplicated template blocks (~70 lines each)
- Extract EntityHistorySection.vue from 3 identical history sections in edit pages
- Extract useDragReorder composable from 4 identical drag-and-drop implementations in StructureNodeEditor (~330 lines → ~30)
- Extract catalogDisplayUtils.ts (resolvePrimaryDocument, resolveSupplierNames, buildSuppliersDisplay)
- Remove redundant computed wrappers (historyEntries, loadingTypes, selectedFiles)
- Remove unused imports (fieldKey, historyActionLabel, formatHistoryDate, *HistoryEntry types)
- Move Intl.DateTimeFormat to module-level in date.ts

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/shared/utils/catalogDisplayUtils.ts

@@ -0,0 +1,87 @@
+import { isImageDocument, isPdfDocument } from '~/utils/documentPreview'
+
+/**
+ * Selects the best document for thumbnail preview from an entity's documents array.
+ * Default priority: PDF first, then images. Use `preferImages` to reverse.
+ */
+export const resolvePrimaryDocument = (entity: Record<string, any>, preferImages = false): any | null => {
+  const documents = Array.isArray(entity?.documents) ? entity.documents : []
+  if (!documents.length) return null
+  const normalized = documents.filter((doc: any) => doc && typeof doc === 'object')
+  const withPath = normalized.filter((doc: any) => doc?.fileUrl || doc?.path)
+  if (!withPath.length) return normalized[0] ?? null
+  const first = preferImages ? isImageDocument : isPdfDocument
+  const second = preferImages ? isPdfDocument : isImageDocument
+  const a = withPath.find((doc: any) => first(doc))
+  if (a) return a
+  const b = withPath.find((doc: any) => second(doc))
+  if (b) return b
+  return withPath[0]
+}
+
+/**
+ * Builds alt text for a document preview thumbnail.
+ */
+export const resolvePreviewAlt = (entity: Record<string, any>): string => {
+  const parts = [entity?.name, entity?.reference].filter(Boolean)
+  return parts.length ? `Aperçu du document de ${parts.join(' – ')}` : 'Aperçu du document'
+}
+
+/**
+ * Supplier name resolution: extracts unique supplier names from entity relations.
+ */
+export const resolveSupplierNames = (entity: Record<string, any>, nestedKey?: string): string[] => {
+  const names: string[] = []
+  const seen = new Set<string>()
+
+  const pushName = (maybeName: unknown) => {
+    if (typeof maybeName !== 'string') return
+    const normalized = maybeName.trim().replace(/\s+/g, ' ')
+    if (!normalized.length) return
+    const key = normalized.toLowerCase()
+    if (seen.has(key)) return
+    seen.add(key)
+    names.push(normalized)
+  }
+
+  const collectConstructeurs = (value: unknown): void => {
+    if (!value) return
+    if (Array.isArray(value)) { value.forEach(collectConstructeurs); return }
+    if (typeof value === 'string') { pushName(value); return }
+    if (typeof value === 'object') {
+      const record = value as Record<string, any>
+      pushName(record?.name ?? record?.label ?? record?.companyName ?? record?.company ?? null)
+      if (record?.constructeur) collectConstructeurs(record.constructeur)
+      if (Array.isArray(record?.constructeurs)) collectConstructeurs(record.constructeurs)
+    }
+  }
+
+  const collectFromLabel = (value: unknown): void => {
+    if (typeof value !== 'string') return
+    value.split(/[,;\\/•·|]+/).map(part => part.trim()).filter(Boolean).forEach(pushName)
+  }
+
+  collectConstructeurs(entity?.constructeurs)
+  collectConstructeurs(entity?.constructeur)
+  collectFromLabel(entity?.constructeursLabel)
+  collectFromLabel(entity?.supplierLabel)
+  collectFromLabel(entity?.suppliers)
+
+  if (nestedKey && entity?.[nestedKey]) {
+    const nested = entity[nestedKey]
+    collectConstructeurs(nested?.constructeurs)
+    collectConstructeurs(nested?.constructeur)
+    collectFromLabel(nested?.constructeursLabel)
+    collectFromLabel(nested?.supplierLabel)
+  }
+
+  return names
+}
+
+const MAX_VISIBLE_SUPPLIERS = 3
+
+export const buildSuppliersDisplay = (suppliers: string[]) => {
+  const visible = suppliers.slice(0, MAX_VISIBLE_SUPPLIERS)
+  const overflow = Math.max(suppliers.length - visible.length, 0)
+  return { suppliers, visible, overflow, tooltip: suppliers.length ? suppliers.join(', ') : '' }
+}