Pause or resume anonymous access to an owned node's public shares

Flip the takedown switch, then end the streams it just de-authorized.

The column is the whole mechanism (D-HC-9): the public choke point reads it on every request and the sweep reads it every pass, so the switch is already effective the moment this transaction commits. Terminating the live streams is what makes it effective now rather than at the end of whatever an anonymous visitor is currently streaming — and it happens after the commit, for the reason unlink closes its streams after its own: a close_stream frame outlives the rollback of the transaction that sent it, so a transaction that might still roll back must not send one.

Only the anonymous streams (:meth:ActiveStreamRegistry.by_hosted_node) — never the owner's own dashboard or share session on the same node. Resuming ends nothing: there is nothing de-authorized to end.