OTP application for Candil.
Starts the ETS-based configuration registry (Candil.Config) and
the dynamic supervisor that manages llama-server engines started
via Candil.start_engine/2.
Note: Arrea.Application is NOT listed here because Arrea is a direct
dependency of Candil (mix.exs → {:arrea, "~> 2.1.0"}) and its
mix.exs declares mod: {Arrea.Application, []}. The OTP application
controller starts Arrea.Application automatically as soon as the
application graph boots — no manual Arrea.Supervisor.start_link/1 call
is required. The supervision tree it brings up (Registry, Monitor,
Leader, Arrea.WorkerSupervisor) is available before Candil.Application
starts its own children.