v0.169.0: disk-health card + degradation notification (Lemezek állapota)

Consumes the agent v0.94.0 smart payload (MinAgent floor unchanged; feature-detect
by presence). One pure verdict fn agentapi.DiskVerdictFor shared by the dashboard
card and the 6h check. Card via a 60s /disks TTL cache (anti-smartctl-storm);
unreachable agent -> Nincs adat, page never blocks. disk-health-check (6h) emits
disk_health_degraded on a degradation only vs an in-memory baseline (first run
silent, recovery/UNKNOWN never notify, multi-attr -> one event). No global banner
(deliberate). Pairs with the hub allowlist bump.

Tests: verdict table (>=90 red-proof), notifier emit, check first-run-silent
(red-proof), degradation-once, recovery-silent, UNKNOWN-excluded, FAILING-critical,
nil-smart card, TTL cache.

REUSE.md

@@ -136,6 +136,8 @@
 | `Client.AddNetStorage/ListNetStorage/RemoveNetStorage` | controller/internal/agentapi/client.go | NAS mounts (A1) | Network storage | Password passes through to agent's 0600 cred file; controller NEVER persists it |
 | `agentapi.StatusError` | controller/internal/agentapi/client.go | `{Path, Code}` typed non-2xx GET error | Distinguishing HTTP statuses from transport errors (`errors.As`) | NEVER string-match agent error text — the capability probe keys on `Code==404` |
 | `SupportCache.Supports` / `Client.Supports` | controller/internal/agentapi/features.go | `(ctx, prober, Feature) SupportState` | Agent-capability gate for COUPLED features (route probe, TTL 5m) | 404 ⇒ No; transport/5xx ⇒ Unknown (NEVER refuse on Unknown). New coupled feature = new `featureProbes` row + gate call at the entry point + `MinAgent:` in the CHANGELOG header (publish-train-rules.md). Web layer: `Server.netFeatures` through the `netAgent` seam |
+| `agentapi.DiskVerdictFor` / `DiskVerdict.Label` / `DegradedAttributes` | controller/internal/agentapi/diskverdict.go | `(*SmartSummary) DiskVerdict` | THE shared disk-health verdict (card chip + 6h check) — v0.169.0 | Pure; nil/UNKNOWN → `DiskVerdictUnknown` (Nincs adat, NEVER alarms); percentage_used threshold is **≥90**. Feature-detects the agent's `DiskInfo.Smart` (nil = old agent). Do NOT recompute the verdict inline anywhere |
+| `Server.cachedDisks` / `RunDiskHealthCheck` | controller/internal/web/disk_health.go | `(ctx)` | Card fetch (60s TTL) / the 6h degradation check | Card uses the 60s TTL cache (anti-smartctl-storm); the CHECK fetches FRESH (`fetchDisks`). Test seams: `Server.disksFn` (source) + `Server.diskNotifyFn` (sink). Baseline is in-memory (restart re-baselines) |
 
 ### Notifications / hub sync