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/i18n_cases_a_test.go

@@ -213,6 +213,7 @@ func i18nCasesA() []i18nCase {
 			d["NetLANAddress"], d["NetSMBName"], d["NetGateway"] = "192.168.1.10", "FELHOM", "192.168.1.1"
 			d["MemorySupported"], d["MemoryReachable"] = true, true
 			d["MemoryAllocatedMB"], d["MemoryUsageMB"], d["MemoryMinMB"], d["MemoryMaxMB"] = 4096, 2048, 2048, 8192
+			d["PowerOffSupported"] = true // R-998: the power-off card with its button
 			return d
 		}},
 		{"settings_system_failed", "settings_system", func() map[string]interface{} {
@@ -223,6 +224,7 @@ func i18nCasesA() []i18nCase {
 			d["RegistryAnonymous"] = false
 			d["LastUpdateState"] = map[string]interface{}{"Status": "failed", "Error": "pull failed"}
 			d["MemorySupported"], d["MemoryReachable"], d["MemoryProcMB"] = true, false, 4096
+			d["PowerOffSupported"] = true
 			return d
 		}},
 		{"settings_system_pending", "settings_system", func() map[string]interface{} {
@@ -231,11 +233,13 @@ func i18nCasesA() []i18nCase {
 			d["SelfUpdateEnabled"] = true
 			d["LastUpdateState"] = map[string]interface{}{"Status": "pending"}
 			d["MemorySupported"], d["MemoryReachable"], d["MemoryProcMB"] = true, false, 0
+			d["PowerOffSupported"] = true
 			return d
 		}},
 		{"settings_system_nomemory", "settings_system", func() map[string]interface{} {
 			d := i18nLayoutData("settings", "Rendszer beállítások")
 			d["MemorySupported"] = false
+			d["PowerOffSupported"] = false // R-998: an old agent — the card's one-line note instead of the button
 			return d
 		}},
 		{"settings_security_full", "settings_security", func() map[string]interface{} {