v0.3.0

Zerover: breaking changes bump the minor until 1.0.

Breaking. The API group moved from apps.understudy.dev to
apps.understudy.sh, because the old domain belongs to an unrelated party. The
annotation and label keys moved with it. Existing installs need the old
custom resource definition deleted and their Understudy objects recreated.

The chart is now published, so installing no longer needs a checkout:

helm install understudy oci://ghcr.io/kylan11/charts/understudy \
  --namespace understudy-system --create-namespace

The image is built for arm64 and amd64. Documentation covering the mechanism,
the signal contract and the failure behaviour is in docs/how-it-works.md.