After the DB writes that record the multi-home edge, calls the docker
SDK directly to add an interface to the base container's netns:
client.networks.get(<topology bridge>).connect(<base>, ipv4_address=ip)
Non-destructive — the base keeps running, no recreate. Service
containers automatically see the new interface because they share
the base's netns via network_mode: service:<base>.
Idempotency: docker APIError with 'already' / 'endpoint exists' is
logged at info and treated as success. Other errors log + leave the
DB row in place; an operator retry will hit the same path.
anti
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