fix: propager le type réel du métachamp Shopify pour éviter les erreurs 422

src/lib/shopifyMetafields.ts

@@ -35,7 +35,7 @@ export function matchMetafields(columnHeaders: string[], definitions: MetafieldD
     const key = normalizeMetafieldKey(header)
     const def = definitions.find(d => d.key === key)
     if (def) {
-      matched[header] = { columnHeader: header, action: 'map', namespace: def.namespace, key: def.key, existingDefinitionId: def.id }
+      matched[header] = { columnHeader: header, action: 'map', namespace: def.namespace, key: def.key, type: def.type, existingDefinitionId: def.id }
     } else {
       unmatched.push(header)
     }
@@ -149,7 +149,7 @@ export async function setProductMetafield(
     method: 'POST',
     headers,
     body: JSON.stringify({
-      metafield: { namespace: resolution.namespace, key: resolution.key, value, type: 'single_line_text_field' },
+      metafield: { namespace: resolution.namespace, key: resolution.key, value, type: resolution.type ?? 'single_line_text_field' },
     }),
   })
   if (!res.ok) {

src/types/creation.ts

@@ -33,6 +33,7 @@ export interface MetafieldResolution {
   action: 'create' | 'map' | 'skip'
   namespace: string               // "custom" par défaut
   key: string                     // clé normalisée
+  type?: string                   // type Shopify réel, ex: 'multi_line_text_field', 'number_decimal'
   existingDefinitionId?: string   // si action === 'map'
 }