v0.95.0: SMART coverage — union-path drives + LVM/dm root + device model

Implements SPIKE-smart-coverage-2026-07-25 fixes B+A (additive; MinAgent unchanged).
Fix B: storage.SmartReader.SMARTForBacking wired into the /disks union path (localapi
Smart seam) so registry/USB drives get a real SMART read (watchdog Known stays
enrich-free). Fix A: smartDeviceFor resolves dm/LVM to the whole disk via
/sys/block/<dm>/slaves (recursive; skips >1-disk); the builtin local dir on the LVM
root gets a SMART-only device from its containing filesystem (never touches
backing/durable_id). SmartSummary.ModelName captured from smartctl. Fix C (-d sat)
stays rejected. Tests + red-proofs (dm multi-disk skip, enrich smartHint, union
routing); Known-path-never-SMARTs asserted.

internal/storage/smart.go

@@ -11,6 +11,7 @@ import (
 // presence so an absent section (e.g. NVMe fields on a SATA disk, or no SMART at all on a
 // USB bridge) decodes cleanly to nil and we degrade to UNKNOWN.
 type smartctlJSON struct {
+	ModelName   *string `json:"model_name"`
 	SmartStatus *struct {
 		Passed bool `json:"passed"`
 	} `json:"smart_status"`
@@ -64,6 +65,9 @@ func parseSMART(raw []byte) hub.SmartSummary {
 			s.Health = hub.SmartFailing
 		}
 	}
+	if j.ModelName != nil && *j.ModelName != "" {
+		s.ModelName = j.ModelName
+	}
 	if j.Temperature != nil && j.Temperature.Current != nil {
 		s.TemperatureC = j.Temperature.Current
 	}