operator hit 'Address already in use (os error 98)' on a harness
restart — the new harness raced the old socket's release. add a
bind_with_retry helper that backs off (250ms doubling, capped at
2s, 12 tries ≈ 22s total) on AddrInUse before giving up. applied
to both the per-agent web UI and the hive-c0re dashboard.
proper fix would be SO_REUSEADDR via socket2 but retry covers the
TIME_WAIT case fine and keeps the dep count down. Other bind errors
still fail immediately (port permission, fd exhaustion).
2146e47770