refactor(catalog) : extract shared delete impact logic and cleanup dead code

Extract duplicated resolveDeleteImpact/buildDeleteMessage into shared utility,
remove redundant computed wrappers, fix indentation, and remove dead code.

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

app/shared/utils/deleteImpactUtils.ts

@@ -0,0 +1,19 @@
+export const resolveDeleteImpact = (entity: Record<string, any>): string[] => {
+  const impacts: string[] = []
+  const machineLinks = Array.isArray(entity?.machineLinks) ? entity.machineLinks.length : entity?.machineLinksCount ?? 0
+  const documents = Array.isArray(entity?.documents) ? entity.documents.length : entity?.documentsCount ?? 0
+  const customFields = Array.isArray(entity?.customFieldValues) ? entity.customFieldValues.length : entity?.customFieldValuesCount ?? 0
+  if (machineLinks > 0) impacts.push(`${machineLinks} liaison${machineLinks > 1 ? 's' : ''} machine`)
+  if (documents > 0) impacts.push(`${documents} document${documents > 1 ? 's' : ''}`)
+  if (customFields > 0) impacts.push(`${customFields} valeur${customFields > 1 ? 's' : ''} de champs personnalisés`)
+  return impacts
+}
+
+export const buildDeleteMessage = (entityName: string, impacts: string[]): string => {
+  const lines = [`Voulez-vous vraiment supprimer « ${entityName} » ?`]
+  if (impacts.length) {
+    lines.push(`Cela supprimera également :\n• ${impacts.join('\n• ')}`)
+  }
+  lines.push('Cette action est irréversible.')
+  return lines.join('\n\n')
+}