Implement App model and three endpoint methods: list_apps (paginated),
get_app (by ID), and batch_get_apps (up to 100 by IDs). Add
comprehensive tests for success, pagination, not-found, and batch
scenarios.
Implement ping() method on OnspringClient. Set up wiremock-based test
infrastructure with shared setup helper. Add tests for success and
unauthorized scenarios verifying correct headers are sent.
Stevan Freeborn