feat(hiboutik): add Hiboutik API client, repositories and DTOs

HiboutikClient handles Basic auth and walks paginated endpoints. One read-only repository per entity (brands, categories, suppliers, products, stocks, customers).

src/models/hiboutikDTO/stock.hiboutik.dto.ts

@@ -0,0 +1,10 @@
+/** Available stock of one product size, as returned by Hiboutik `GET /stock_available/all_wh` (all warehouses). */
+export interface StockHiboutikDto {
+  product_id: number;
+  /** Size id, 0 for a product without sizes. */
+  product_size: number;
+  /** Decimal as a string, e.g. "3". Stays at 0 while stock management is disabled in Hiboutik. */
+  stock_available: string;
+  product_barcode: string;
+  product_supplier_reference: string;
+}