Silently priming the first observation of a skipped provider fixed the
duplicate alert but introduced the opposite fault: an incident that began
or worsened while the provider was still refreshing became the baseline
and never notified.

The root cause is that resetNotificationMemo dropped provider status along
with the threshold-derived state, even though a settings change is not a
status transition. Status keys now survive the reset, and primeNotifications
carries an existing baseline across a provider it skips. Silent priming is
therefore limited to a genuine first observation, where no prior knowledge
exists.

Behaviour by scenario, given a threshold change during a pending refresh:
an unchanged ongoing incident stays quiet, an incident that starts or
worsens during the interval notifies through the existing worsened and
incidentChanged paths, and a cold start with no baseline primes silently.

Both invariants get static assertions, verified to fail when the reset
wipes the whole memo and when the carry-forward is removed.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>