feat(reference-auto) : display referenceAuto in piece views + formula config in ModelTypeForm

- Piece interface: add referenceAuto field
- piece/[id].vue: read-only display with auto badge
- pieces/[id]/edit.vue: disabled input when referenceAuto is set
- pieces-catalog.vue: new column "Réf. auto"
- PieceItem.vue: badge + detail line for referenceAuto
- ModelTypeForm.vue: formula + required fields config for PIECE category
- modelTypes.ts: add referenceFormula/requiredFieldsForReference to types

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

app/pages/piece/[id].vue

@@ -113,6 +113,17 @@
             </div>
           </div>
 
+          <!-- Référence auto (read-only, shown only if computed) -->
+          <div v-if="piece.referenceAuto" class="form-control">
+            <label class="label">
+              <span class="label-text">Référence auto</span>
+            </label>
+            <div class="input input-bordered input-sm md:input-md bg-base-200 flex items-center gap-2">
+              <span class="font-mono font-semibold">{{ piece.referenceAuto }}</span>
+              <span class="badge badge-sm badge-ghost">auto</span>
+            </div>
+          </div>
+
           <!-- Référence + Fournisseurs (if value or edit mode) -->
           <div
             v-if="isEditMode || piece.reference || editionForm.constructeurIds.length"

app/pages/pieces-catalog.vue

@@ -69,6 +69,10 @@
             {{ row.piece.reference || '—' }}
           </template>
 
+          <template #cell-referenceAuto="{ row }">
+            {{ row.piece.referenceAuto || '—' }}
+          </template>
+
           <template #cell-description="{ row }">
             <div v-if="row.piece.description" class="group relative">
               <span class="block cursor-help truncate">{{ row.piece.description }}</span>
@@ -174,6 +178,7 @@ const columns = [
   { key: 'preview', label: 'Aperçu', width: 'w-24' },
   { key: 'name', label: 'Nom', sortable: true },
   { key: 'reference', label: 'Référence' },
+  { key: 'referenceAuto', label: 'Réf. auto' },
   { key: 'description', label: 'Description' },
   { key: 'suppliers', label: 'Fournisseurs' },
   { key: 'typePiece', label: 'Type de pièce', filterable: true, filterPlaceholder: 'Filtrer…' },

app/pages/pieces/[id]/edit.vue

@@ -114,6 +114,19 @@
             >
           </div>
 
+          <div v-if="piece?.referenceAuto" class="form-control">
+            <label class="label">
+              <span class="label-text">Référence auto</span>
+            </label>
+            <input
+              :value="piece.referenceAuto"
+              type="text"
+              class="input input-bordered input-sm md:input-md bg-base-200"
+              disabled
+              title="Générée automatiquement à partir du type et des champs personnalisés"
+            >
+          </div>
+
           <div class="form-control">
             <label class="label">
               <span class="label-text">Fournisseur</span>