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/translation/zh-TW.json

@@ -1309,6 +1309,7 @@
       "smtpErrorRelay": "伺服器拒絕從此地址傳送",
       "smtpErrorEof": "連線已被伺服器關閉",
       "smtpErrorUnknown": "SMTP 錯誤：{{ .Error }}",
+      "eventMemoryHigh": "記憶體使用率高 (%)",
       "remarkTemplate": "備註範本",
       "remarkTemplateDesc": "設定後，這將取代每個訂閱連結的備註模型——使用變數標記撰寫您自己的格式（使用按鈕來插入）。留空則使用上方的模型。"
     },
@@ -1865,7 +1866,7 @@
       "idDesc": "顯示您的 Telegram ID"
     },
     "messages": {
-      "cpuThreshold": "🔴 CPU 使用率為 {{ .Percent }}%，超過閾值 {{ .Threshold }}%",
+      "cpuThreshold": "CPU 使用率為 {{ .Percent }}%，超過閾值 {{ .Threshold }}%",
       "selectUserFailed": "❌ 使用者選擇錯誤！",
       "userSaved": "✅ 電報使用者已儲存。",
       "loginSuccess": "✅ 成功登入到面板。\r\n",
@@ -1940,7 +1941,8 @@
       "eventNodeUp": "節點 {{ .Name }} 已上線",
       "eventCPUHigh": "CPU 偏高",
       "eventCPUHighDetail": "CPU：{{ .Detail }}",
-      "eventLoginFallback": "來自 {{ .Source }} 的登入失敗"
+      "eventLoginFallback": "來自 {{ .Source }} 的登入失敗",
+      "memoryThreshold": "記憶體使用率 {{ .Percent }}% 超過閾值 {{ .Threshold }}%"
     },
     "buttons": {
       "closeKeyboard": "❌ 關閉鍵盤",
@@ -2043,4 +2045,4 @@
     "statusDown": "中斷",
     "statusUp": "恢復"
   }
-}
+}