Unwraps org.bluez D-Bus property maps (as decoded by rebus) into plain Elixir maps for Bluez.Advert.

rebus decodes an a{sv} dict to a list of {key, {signature, value}} and a variant to {signature, value}. This module strips those wrappers, with two special cases that are themselves nested dicts of byte arrays:

• ManufacturerData (a{qv}): [{company_id, {"ay", bytes}}] → %{company_id => binary}
• ServiceData (a{sv}): [{uuid, {"ay", bytes}}] → %{uuid => binary}

Pure and host-testable — this is the main parse seam between raw D-Bus wire data and advert reconstruction.