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.

cmd/felhom-agent/main.go

@@ -1285,8 +1285,9 @@ func buildLocalAPIServer(cfg config.Config, px *proxmox.Client, store *backup.St
 		Backups:       runner,
 		Store:         store,
 		Storage:       observer,
-		DriveTargets:  driveTargets,                // Impl-2a: registry+units drives for the /disks view (union w/ Observe storages)
-		HostReader:    storage.NewProcHostReader(), // Impl-2b: durableIDForMount raw-mount fallback + role gate
+		DriveTargets:  driveTargets,                    // Impl-2a: registry+units drives for the /disks view (union w/ Observe storages)
+		Smart:         storage.NewSmartReader(hostOps), // v0.95.0 Fix B: SMART for the union-path drives
+		HostReader:    storage.NewProcHostReader(),     // Impl-2b: durableIDForMount raw-mount fallback + role gate
 		Tokens:        tokens,
 		BackupCadence: cfg.Backup.BackupCadence(),
 		// Disk management (slice 8C): the privileged host surface + the data-bearing wipe gate.