feat(memory): add memory threshold alerts (#5366)

* feat(memory): add memory threshold alerts

Add memory (RAM) threshold alerts following the same architecture as
CPU alerts: CheckMemJob with @every 1m cadence, memoryAlarmWanted gate,
tgMemory/smtpMemory per-subscriber settings (default 80%), EventBusCheckboxes
with inline threshold input, i18n for en-US/ru-RU with English defaults.

# Conflicts:
#	internal/web/translation/ar-EG.json
#	internal/web/translation/es-ES.json
#	internal/web/translation/fa-IR.json
#	internal/web/translation/id-ID.json
#	internal/web/translation/ja-JP.json
#	internal/web/translation/pt-BR.json
#	internal/web/translation/ru-RU.json
#	internal/web/translation/tr-TR.json
#	internal/web/translation/uk-UA.json
#	internal/web/translation/vi-VN.json
#	internal/web/translation/zh-CN.json
#	internal/web/translation/zh-TW.json

* fix: address code review findings for memory alerts

- Remove dead settingService field from CheckMemJob
- Fix cpuThreshold double-emoji in 12 locale files (code prepends 🔴)
- Align TgCpu/TgMemory fields in entity.go
- Add missing SetTgMemory function

* fix: restore settingService in CheckMemJob for consistency with CheckCpuJob

internal/web/web.go

@@ -290,7 +290,8 @@ const (
 	cadenceCheckHash     = "@every 2m"
 	// cpu.Percent samples over a full minute (blocking), so a finer cadence just
 	// stacks overlapping samplers; subscribers rate-limit alerts to 1/min anyway.
-	cadenceCPUAlarm = "@every 1m"
+	cadenceCPUAlarm    = "@every 1m"
+	cadenceMemoryAlarm = "@every 1m"
 )
 
 // startTask schedules background jobs (Xray checks, traffic jobs, cron
@@ -385,6 +386,10 @@ func (s *Server) startTask(restartXray bool) {
 	if s.cpuAlarmWanted() {
 		s.cron.AddJob(cadenceCPUAlarm, job.NewCheckCpuJob())
 	}
+	// Memory monitor publishes memory.high events; register it whenever any notifier wants them.
+	if s.memoryAlarmWanted() {
+		s.cron.AddJob(cadenceMemoryAlarm, job.NewCheckMemJob())
+	}
 }
 
 // cpuAlarmWanted reports whether any notifier is configured to receive cpu.high
@@ -418,6 +423,36 @@ func (s *Server) cpuAlarmWanted() bool {
 	return false
 }
 
+// memoryAlarmWanted reports whether any notifier is configured to receive memory.high alerts.
+func (s *Server) memoryAlarmWanted() bool {
+	wants := func(events string, threshold int) bool {
+		if threshold <= 0 {
+			return false
+		}
+		for _, e := range strings.Split(events, ",") {
+			if strings.TrimSpace(e) == string(eventbus.EventMemoryHigh) {
+				return true
+			}
+		}
+		return false
+	}
+	if on, _ := s.settingService.GetTgbotEnabled(); on {
+		events, _ := s.settingService.GetTgEnabledEvents()
+		mem, _ := s.settingService.GetTgMemory()
+		if wants(events, mem) {
+			return true
+		}
+	}
+	if on, _ := s.settingService.GetSmtpEnable(); on {
+		events, _ := s.settingService.GetSmtpEnabledEvents()
+		mem, _ := s.settingService.GetSmtpMemory()
+		if wants(events, mem) {
+			return true
+		}
+	}
+	return false
+}
+
 // Start initializes and starts the web server with configured settings, routes, and background jobs.
 func (s *Server) Start() (err error) {
 	return s.start(true, true)