fix(piece) : persist slot quantity on blur and send prix as string

- Save composant piece slot quantity via PATCH on blur
- Pass slotId through hierarchy and selection entries
- Send prix as string (not number) to match backend expectation
- Show quantity in view mode when > 1
- Allow quantity edit for all pieces (not just root-level)

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

app/composables/useComponentEdit.ts

@@ -7,6 +7,7 @@ import { useProductTypes } from '~/composables/useProductTypes'
 import { usePieces } from '~/composables/usePieces'
 import { useProducts } from '~/composables/useProducts'
 import { useCustomFields } from '~/composables/useCustomFields'
+import type { SelectionEntry } from '~/shared/utils/structureSelectionUtils'
 import { useApi } from '~/composables/useApi'
 import { useToast } from '~/composables/useToast'
 import { extractRelationId } from '~/shared/apiRelations'
@@ -53,7 +54,7 @@ const historyFieldLabels: Record<string, string> = {
 export function useComponentEdit(componentId: string) {
   const { canEdit } = usePermissions()
   const router = useRouter()
-  const { get } = useApi()
+  const { get, patch } = useApi()
   const { componentTypes, loadComponentTypes } = useComponentTypes()
   const { pieceTypes, loadPieceTypes } = usePieceTypes()
   const { productTypes, loadProductTypes } = useProductTypes()
@@ -269,6 +270,21 @@ export function useComponentEdit(componentId: string) {
     }
   })
 
+  const saveSlotQuantity = async (entry: SelectionEntry) => {
+    const slotId = entry.slotId
+    const quantity = typeof entry._definition?.quantity === 'number'
+      ? Math.max(1, entry._definition.quantity)
+      : null
+    if (!slotId || quantity === null) return
+    try {
+      await patch(`/composant-piece-slots/${slotId}`, { quantity })
+      toast.showSuccess('Quantité mise à jour')
+    }
+    catch (error: any) {
+      toast.showError(error?.message || 'Erreur lors de la mise à jour de la quantité')
+    }
+  }
+
   const submitEdition = async () => {
     if (!component.value) {
       return
@@ -299,10 +315,6 @@ export function useComponentEdit(componentId: string) {
       payload.prix = null
     }
 
-    if (component.value.structure) {
-      payload.structure = component.value.structure
-    }
-
     saving.value = true
     try {
       const result = await updateComposant(component.value.id, payload)
@@ -457,6 +469,7 @@ export function useComponentEdit(componentId: string) {
     handleFilesAdded,
     refreshDocuments,
     submitEdition,
+    saveSlotQuantity,
     resolvePieceLabel,
     resolveProductLabel,
     resolveSubcomponentLabel,