v0.94.0: serialize per-disk SMART into the /disks payload

Additive, backward-compatible (MinAgent floor unchanged). The SMART is already
computed on the request path (storage.Observe -> enrich); this copies the target's
Smart into localapi.DiskInfo (pointer, omitempty) only when Health != "", so an
unread/absent summary stays omitted and the controller renders "Nincs adat".
No new smartctl load, endpoint, or sudoers change.

Test TestDisks_SmartSerialized + red-proof (drop the copy -> fails).

CHANGELOG.md

@@ -1,3 +1,20 @@
+## v0.94.0 — serialize per-disk SMART into the /disks payload (2026-07-24)
+
+Additive, backward-compatible; **MinAgent floor unchanged** (the controller feature-detects by payload
+presence). No new smartctl load, no new endpoint, no sudoers change — the SMART is already computed on
+the request path (`storage.Observe` → `enrich` runs `smartctl -a -j` for dir-backed targets); this
+release simply copies the target's already-populated `Smart` into `localapi.DiskInfo`.
+
+- `DiskInfo` gains `Smart *hub.SmartSummary \`json:"smart,omitempty"\``. In `handleDisks` the summary is
+  copied **only when `t.Smart.Health != ""`** — a zero-value summary (SMART never read: no smartctl
+  device, USB bridge, or a failed read) stays omitted, so the controller sees *absent* and renders
+  "Nincs adat" rather than a misleading UNKNOWN. The union-in drives (driveTargets.Known path, no
+  enrichment) carry no SMART and are omitted by the same guard.
+- The controller (v0.169.0) consumes this to render a "Lemezek állapota" card + a 6-hourly
+  degradation notification. Old controllers ignore the extra field.
+- Test `TestDisks_SmartSerialized` (payload includes SATA counters + temperature for a fixture target;
+  absent-SMART target omits the field); red-proof: drop the copy → the serialized-Smart assertion fails.
+
 ## v0.93.0 — a recovery code can no longer contain a hyphenated word (2026-07-21)
 
 > **SHIPPED 2026-07-22:** built + published (sha256 `a68b2ff73200622e…`), Day-0-manifest-vouched,