Pure-Elixir parser that walks an APRS digipeater path left-to-right and
emits verified hops for callsigns carrying the used flag (`*`). Filters
Q-constructs, TCPIP/TCPXX, and routing aliases (WIDE/TRACE/RELAY/etc.);
handles anonymous-digi cases, missing station-position lookups, and
self-loops without advancing source past unattributable hops.
Used by upcoming 144 MHz calibration to attribute aprs.me receives to
real digipeater geometry without persisting any APRS data on our side.
Graham McIntire
4a5864f090