fix(ui) : remove legacy edit pages and history composables, unify create/edit forms

Consolidate create and edit pages into single create pages with edit mode support.
Remove obsolete catalog pages, history composables, and fix remaining code review issues.
Include migration to relink orphaned custom fields.

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

frontend/app/composables/useComposants.ts

@@ -4,7 +4,7 @@ import { useApi } from './useApi'
 import { uniqueConstructeurIds } from '~/shared/constructeurUtils'
 import { useConstructeurs, type Constructeur } from './useConstructeurs'
 import { extractRelationId, normalizeRelationIds } from '~/shared/apiRelations'
-import { extractCollection } from '~/shared/utils/apiHelpers'
+import { extractCollection, extractTotal } from '~/shared/utils/apiHelpers'
 
 export interface Composant {
   id: string
@@ -51,17 +51,6 @@ const total = ref(0)
 const loading = ref(false)
 const loaded = ref(false)
 
-const extractTotal = (payload: unknown, fallbackLength: number): number => {
-  const p = payload as Record<string, unknown> | null
-  if (typeof p?.totalItems === 'number') {
-    return p.totalItems
-  }
-  if (typeof p?.['hydra:totalItems'] === 'number') {
-    return p['hydra:totalItems']
-  }
-  return fallbackLength
-}
-
 export function useComposants() {
   const { showSuccess } = useToast()
   const { get, post, patch, delete: del } = useApi()