bug: Agent fails to sync related resources up to kcp

[xrstf]

Describe the bug

Since #15, the agent fails to sync related resources up into kcp:

Reconciler error {"controller": "syncagent-sync", "object": {"name":"my-crontab","namespace":"default"}, "namespace": "default", "name": "my-crontab", "reconcileID": "67948df7-e3a3-4f2f-a97a-5230b1f5ee8a", "error": "failed to process related resource credentials: failed to sync related object: failed to create destination object: failed to ensure destination namespace: failed to check: no kind is registered for the type v1.Namespace in scheme "pkg/runtime/scheme.go:100""}

Steps To Reproduce

1. Configure a PublishedResource with a related resource in it that originates on the "service" side.
2. Observe the agent logs.

Expected Behaviour

Syncing should work.

Additional Context

No response