- ApiClient: add getSuppliers, addSupplier, updateSupplier,
orderSuppliers, deleteSupplier on article namespace
- api/index.js: expose same methods in legacy http client
- StorageManager: add #supplierWatchers Map and watchArticleSuppliers()
backed by article-<sku> SSE signal; wired up as article.supplierWatch
- ArticleTileTab: pass article prop to ArticleSupplierTab
- ArticleSupplierDialog (new): dialog to assign / edit a supplier link
(supplier autocomplete, Lief.-SKU, VPE, stock, EK Netto + MwSt.)
- ArticleSupplierTab: full supplier management table with reordering
(up/down arrows → PUT /supplier/order), inline edit and delete,
stock badge, purchase price display and empty state
