Search supplier sites, Environdec, and EPD Hub for EPD candidates per normalized product.
Reads epd-products.json and epd-suppliers.json, searches for EPD candidates in fixed order (supplier website, then Environdec at environdec.com, then EPD Hub at manage.epdhub.com), merges and ranks results, and writes epd-candidates.json. Uses normalized product names only; empty candidate lists are valid; never invents EPD metadata or PDF URLs.