Resolve a MAC address (or bare OUI prefix) to its IEEE-registered hardware vendor. Accepts any common format — FC:FB:FB:01:02:03, fc-fb-fb-01-02-03, fcfb.fb01.0203, fcfbfb, or a 9-hex MA-S prefix. Uses longest-prefix matching across the IEEE MA-L (24-bit), MA-M (28-bit) and MA-S (36-bit) registries so blocks IEEE has subdivided resolve to the actual manufacturer. Returns the vendor name, the matched OUI prefix and which registry it came from, plus decoded address bits: whether the address is multicast/group, locally administered, or a randomized (privacy) MAC — for which no vendor exists by design. Authoritative bundled IEEE data.