wait_for_address assumed eth0 already existed and polled for an address with a
1s window -> on a fresh boot (smolnetd/driver-manager bring the interface up
async) it spun on a non-existent interface and logged "timed out waiting for
DHCP address on eth0". Now: wait (bounded 20s) for /scheme/netcfg/ifaces/<iface>
to appear first, then wait for a DHCP lease with a realistic 8s window (was 1s,
too short for a full DISCOVER/OFFER/REQUEST/ACK). Both bounded + oneshot_async so
boot never blocks. Pairs with the smolnetd/dhcpd async-NIC-attach fix.
vasilito
c3f8c89856