Count how many of the advanced search drawer's filters are set to a non-default
value: the selected-suppliers, country, shipping, and availability lists when
non-empty, plus the price range when either bound is set. A price min and max
count as a single filter (the price range), mirroring how the drawer groups
them. Boolean behavior toggles and the results limit are intentionally excluded
— this counts the discrete filter categories, matching the drawer's sections.
Count how many of the advanced search drawer's filters are set to a non-default value: the selected-suppliers, country, shipping, and availability lists when non-empty, plus the price range when either bound is set. A price min and max count as a single filter (the price range), mirroring how the drawer groups them. Boolean behavior toggles and the results limit are intentionally excluded — this counts the discrete filter categories, matching the drawer's sections.