An immutable event record in the append-only event log.
Events capture significant actions (message sent, cost recorded, policy violation, etc.) with a type atom and a data map containing type-specific payload.
type
data
@type t() :: %PhoenixAI.Store.EventLog.Event{ conversation_id: String.t() | nil, data: map(), id: String.t() | nil, inserted_at: DateTime.t() | nil, metadata: map(), type: atom(), user_id: String.t() | nil }