v0.12.0

Toise v0.12.0 — the pod

A thirteenth entity type, and the first vocabulary addition since the type set
became something producers import rather than retype. Additive: nothing about
existing types, relations or events changes.

A Kubernetes pod is the unit of scheduling and of failure, and none of the twelve
existing types fits it. Leaving it out and keeping the pod name as a container
attribute was the alternative considered; it fails because an attribute you have
to string-match on is not a join. The argument that settles it is telemetry: the
network namespace is shared per pod, so pod-scoped network measurements describe
the pod and nothing else, and a type that owns telemetry needs an entity to
attach it to.

Identity is the UID Kubernetes assigns, never namespace/name, which is mutable
and reused. No new relation type: a container runs_on its pod, the pod runs_on
its host, and runs_on's impact flows target to source.

Producers get the constant as wire.TypePod in pkg/emit/v0.7.0. Both versions are
needed: the SDK tag lets a producer compile, this release lets it emit.

Verified end to end on a live instance before tagging: a pod emitted over OTLP is
accepted, the container-to-pod-to-host chain traverses, and impact_of on the node
returns the pod and its container.