ed97232598
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.