refactor: FP patterns in packets_live/callsign_view
- mount: extract subscribe_if_connected/2, split assign_valid/assign_invalid
to eliminate inline if/else for validation + subscription logic.
- enrich_packet_with_device_identifier: extract resolve_canonical_identifier/1
as multi-clause function (binary guard + catch-all) instead of nested if.
- update_packet_lists: cond → multi-clause do_update/4 with guards.
Three explicit paths: at-cap no-stored, at-cap with-stored, under-cap.
- get_timestamp_microseconds: case → multi-clause (%DateTime{}, binary,
catch-all) for cleaner dispatch.
Graham McIntire
088fd20711