Adds the Notifications e2e suite under tests/e2e/Services/Notifications.
Asserts that the live notifications queue depth is reported via
GET /v1/health/queue/notifications, that the threshold guard is honoured,
and that the failed-jobs endpoint accepts the v1-notifications queue name.
Dispatch routing, dedup, and webhook signing are covered by the unit
suite — the worker cannot be deterministically driven through the live
queue from a test client without an admin enqueue endpoint, so the e2e
file pins the public health contract that ops dashboards and KEDA scale
on.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
