APRS object packets (e.g. DAPNET transmitters) were showing the
sender's callsign on the map instead of the object name. For example,
DB0SDA (Germany) sending an object for P-K5SGD (Texas) would display
as "DB0SDA" at the Texas coordinates.
- Add display_name/1 to PacketUtils that returns object_name for
objects, item_name for items, falling back to sender
- Update DataBuilder to use display_name in all callsign display paths
- Fix object/item detection order in packet_consumer to prevent
objects from being incorrectly flagged as items
- Add DataBuilder tests for object/item display name behavior
- Fix flaky PacketPipelineSupervisor test (ensure module loaded)
