The detect side of the self-healing loop, modeled on the strategy engine: a
pure assess() turns breaching telemetry samples into RegressionObservations
(with a stable per-signal fingerprint for later dedupe), and run_cycle() is a
no-op unless self_heal_enabled and otherwise only sends the CEO one
ack-notification per regression. Detect + notify only — it never originates,
starts, merges, or deploys; the telemetry source is injectable for testing.
6 unit tests.
