ReadAsync internally subscribes/unsubscribes the same ScanTime tag used
by the persistent probe, which was tearing down the probe subscription
and triggering false reconnects every ~5s. Guard UnsubscribeInternal and
stored subscription state so the probe tag is never removed by other
callers. Also removes DetailedHealthCheckService (redundant with the
persistent probe), adds per-instance config files (appsettings.v2.json,
appsettings.v2b.json) loaded via LMXPROXY_INSTANCE env var so deploys
no longer overwrite port settings.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Subscription metrics (totalDelivered, totalDropped) now visible in
/api/status JSON and HTML dashboard. Card turns yellow if drops > 0.
Aggregated from per-client counters in SubscriptionManager.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
