fix(alerts): preserve storage incidents when connectivity is unknown

Do not count empty or unknown storage status as recovery evidence. Normalise status spelling for connectivity checks while leaving capacity evaluation independent and preserving existing inactive/disabled storage behaviour.

Change-source: pulse-maintainer

docs/release-control/v6/internal/subsystems/alerts.md

@@ -1390,6 +1390,16 @@ health checks, and storage offline lifecycle handling; future storage alert
 behavior should extend that resource checker owner while shared storage-health
 assessment helpers remain package-level until host and storage health paths are
 separated cleanly.
+Storage connectivity status is trimmed and case-normalised before evaluation.
+Empty or `unknown` status is absent connectivity evidence: it must not advance
+recovery or replace an existing incident's identity/start time. Capacity and
+pool-health evaluation remain independent and may still use valid observations.
+The existing non-failing treatment of available, online, active, inactive and
+disabled statuses remains unchanged; explicit connectivity-disable policy still
+clears the incident. `TestStorageUnknownConnectivityDoesNotRecover` and
+`TestStorageKnownConnectivityRecoveryCompatibility` in
+`internal/alerts/alerts_test.go` pin unknown-observation preservation, independent
+capacity activation, normalised offline activation and confirmed recovery.
 Proxmox node alert evaluation now lives in `internal/alerts/node.go`. That file
 owns node metric and temperature projection, node offline lifecycle handling,
 host-agent deduplication bookkeeping, and instance-scoped node display-name