v0.6.2: merge duplicate per-packet link lock on the Data receive path Follow-up to v0.6.1: handle_incoming locked the same per-link mutex twice per incoming Data packet (remote-address check, then a separate record_rx lock). Merged into one acquisition. Live strace after v0.6.1 showed futex contention essentially unchanged on both production hosts, so this closes the matching gap on the receive side.