Codes are accepted exactly as printed: leading zeros, spaces and hyphens
are ignored. Needs a signed-in BasketWatch account.

Args:
    codes: one barcode, or up to 100 separated by commas
        (e.g. "5000127014084" or "5000127014084,5000157024671").
    store: optionally restrict to one of "aldi", "tesco", "supervalu",
        "dunnes".
    include_copy: also return ingredients and per-100g nutrition where
        the retailer publishes them.

Returns {"products": [...], "not_found": [...], "invalid": [...]}. Each
product row carries store, matched_barcodes, name, brand, pack_size,
price and its full barcodes list. One credit per barcode found, however
many retailers stock it; codes with no match cost nothing.