fix: use product name as VK description fallback (VK requires ≥10 chars)

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

web/tasks/vk_sync.py

@@ -151,7 +151,7 @@ def _sync_product(
 ) -> None:
     name = _name_for_vk(product.name)
     price_rubles = _calc_price(product.price)
-    desc = (product.description or "").strip()
+    desc = product.name
     stock = settings.VK_STOCK_AMOUNT if product.allow_to_sell else 0
     owner_id = f"-{vk_group_id}"
     now = _now()