Starts the library's process tree:

• Amarula.ProfileRegistry — the app-level profile -> Connection pid registry that enforces one connection per profile (per node) and gives consumers a restart-safe handle (refer to a connection by its :profile, not a raw pid).
• Amarula.InstanceRegistry — the app-level registry that names every per-connection tree's infrastructure by the connection's instance_id ref: the tree supervisor, the sibling roles (Connection, sender supervisor), and each recipient's ConversationSender. Keying by the ref directly (not a hashed atom) means no atom is minted per connection and two connections can never collide.
• Amarula.ConnectionsSupervisor — a DynamicSupervisor that owns every per-connection tree. Connection trees are started here (not linked to the caller of connect/2), so a connection crash is observable by the consumer via events but never propagates an exit signal that kills it.

A clustered consumer that wants one-connection-per-profile cluster-wide can supply its own registry module via the :registry connection config (e.g. Horde.Registry); see Amarula.Config. The default local Registry enforces uniqueness per node only.