Retire runtime/API/UI monitored-system volume enforcement now that infrastructure monitoring is no longer capped.
Keep only legacy metadata scrubbing and purchase-start compatibility for old max_monitored_systems references.
Rename the remaining preview surface to monitored-system impact and make previews explanatory rather than save-blocking.
Update subsystem contracts and RA7 evidence for the caps-retired invariant.
v5-migrated installations can persist a legacy max_monitored_systems value
(e.g. Community=1) in the license claims. After 5914a4127 made all
self-hosted tiers uncapped, EffectiveLimits() only scrubbed Lifetime and
v5-grandfathered Pro, so migrated Community / Pro / Relay installs kept
emitting the old cap and the "Over plan" banner still rendered on rc.2.
Extend the scrub to every self-hosted tier whose TierMonitoredSystemLimits
entry is 0, and stop monitoredSystemContinuityStatusLocked() from falling
back to the grant's plan limit when the license says uncapped. 0 is now
a first-class "unlimited" signal, not a missing-data sentinel.
The grandfather-floor continuity is still captured for audit, but no
longer enforces on self-hosted tiers. Cloud and MSP limit resolution is
untouched.
Refs #1429
rcourtman