Rename internal/{checker,service,provider,notification} to
internal/{dnschecker,serviceanalyzer,providerregistry,notifier} so
imports no longer collide with the same-named usecase subpackages and
no longer require import aliases to disambiguate.
For providers that manage SOA serials (like AXFRDDNS), re-fetch the
zone after applying corrections to capture the real published state.
The snapshot and WIP zone's Origin service are both updated with the
actual serial.
This is gated on a new "manages-soa-serial" capability, preserving
the existing behavior for providers that abstract SOA handling.
Closes: https://github.com/happyDomain/happydomain/issues/35
- Moved usecases into internal/usecase
- Renamed internal/utils to internal/helpers for better naming semantics
- Clarified separation between domain model, usecases, adapters, and web/API
