Subscribes to cluster adaptor-change broadcasts and evicts matching local Cachex entries, keeping each node coherent with Postgres.

Subscribes to opts[:source_topic] on Lightning.PubSub at init. On {:changed, name, source} it deletes every cache key Lightning.Adaptors.Store writes for that name, plus the source-wide :packages and :catalogue keys, which any change invalidates. Dropping :icon_bytes is what lets a committed icon error clear. Only the row moving can resolve it, and the row moving always broadcasts. There is no source filtering. A broadcast for a source not active on this node deletes keys that do not exist, which is a no-op.