v0.310.0: „A gép kikapcsolása" — the household turns the whole machine off (R-998); honest restart text (R-999)

POST /api/server/poweroff (dashboard login, POST only, the typed word KIKAPCSOLÁS / TURN OFF)
→ agent POST /host/poweroff (MinAgent 0.155.0; hidden for an older agent). The controller refuses
during its own backup/restore/app update; the agent's reasons are shown as household sentences.
„Kiszolgáló újraindítása" becomes „A Felhom újraindítása" and says it restarts the Felhom part;
/api/server/reboot is POST only (R-983). Tests red-proofed; parity fixtures regenerated on purpose.

controller/internal/web/server.go

@@ -201,6 +201,10 @@ type Server struct {
 	memFeatures agentapi.SupportCache
 	memAgentFn  func() (memAgent, error)
 
+	// R-998: test seams for the power-off route (nil in production → the real agent client / busy checks).
+	powerOffAgentFn func() (powerOffAgent, error)
+	powerOffBusyFn  func() (bool, string)
+
 	// Asset syncer for Hub-managed assets (optional)
 	assetsSyncer *assets.Syncer