DNS-only seeds burst-die (64 peers, 2s cumulative handshake timeout) and TBC
makes no dials at all; the header restore then stalls (968254 on 2026-09-29,
967460 on 2026-09-22) and op-node wedges on 'failed to fetch previous keystone'
because canonical BTC headers are missing from full TBC.
Pinned list matches the proven host-local workaround on us-16, where an nft
redirect (192.168.0.0/26:8333 -> :18333) serves /root/hemi-tbc-header-peer.py,
so these addresses only need to be dialable, not real bitcoin nodes. Landing
them in the tracked compose because regens wipe the .env COMPOSE_FILE append
(observed 09-29 03:06 and 03:56 UTC).