feat(notifications): event bus architecture with Telegram and SMTP subscribers (#5326)

* feat(notifications): event bus architecture with Telegram and SMTP subscribers

- Event bus core with buffered channel, fan-out, panic recovery
- Telegram subscriber with HTML formatting and rate limiting
- Email subscriber with SMTP/TLS/STARTTLS support and stage diagnostics
- 5 event types: outbound.down/up, xray.crash, cpu.high, login.attempt
- CPU threshold checks per subscriber (tgCpu for TG, smtpCpu for Email)
- SystemMetricData struct for raw metric values in events
- i18n keys for en-US, ru-RU, and English defaults for other locales

* fix

* fix(notifications): repair crash/CPU alerts, harden secrets, add node alerts

Bug fixes:
- Xray crash notifications were permanently suppressed after the first crash:
  XrayStateTracker latched state="down" with no reset and no recovery event,
  so only the first crash per process lifetime ever notified. Removed the
  tracker; the existing 1/min rate limiter already dedupes crash-loop spam.
- Email CPU alerts could never fire unless Telegram was also enabled, because
  the CPU job was registered only inside the tgbot block. Register it whenever
  either Telegram or SMTP wants cpu.high (new cpuAlarmWanted gate) and relax
  the cadence to @every 1m (cpu.Percent already samples over a full minute).
- SMTP password (and, pre-existing, all other secrets) were shipped to the
  browser in plaintext: GetAllSettingView was dead code and /setting/all
  returned the raw model. Wire getAllSetting -> GetAllSettingView, redact
  smtpPassword with a hasSmtpPassword presence flag, and preserve it on blank
  save. Closes the leak for tgBotToken/ldapPassword/2FA token too.

Polish:
- email Send: use nil SMTP auth when no credentials (Go refuses PlainAuth over
  the unencrypted "none" transport).
- Remove unused EventClientDepleted; fix inaccurate bus.go doc comments; drop
  stale tgBotLoginNotify from the frontend schema; gofmt alignment.

Feature - node online/offline alerts:
- Emit node.down/node.up from the heartbeat job on a real status transition
  (with a startup-spam guard), reusing NodeHealthData. Formatted by both the
  Telegram and email subscribers and selectable in the settings UI.

Regenerated frontend types (hasSmtpPassword). New i18n keys added to en-US;
other locales fall back to English (bundle default) until translated.

* fix(settings): use antd Space orientation instead of deprecated direction

Ant Design 6 deprecated Space's `direction` prop in favor of `orientation`,
which logged a console warning from the Telegram/Email notification tabs. Brings
these two tabs in line with the rest of the codebase, which already uses
`orientation`.

* i18n(notifications): translate the notification feature into all locales

The notifications PR shipped ~99 new strings (SMTP settings, event labels,
Telegram/email message templates) as English placeholders in every non-English
locale. Translate them — plus the node-alert keys added during this review —
into all 12 locales: Arabic, Spanish, Persian, Indonesian, Japanese,
Portuguese-BR, Russian, Turkish, Ukrainian, Vietnamese, and Simplified/
Traditional Chinese.

Go-template placeholders ({{ .Tag }}, {{ .Name }}, etc.) are preserved exactly;
tgbot message values carry no leading status emoji (the bot/email code adds
those, so an emoji in the value would duplicate it); product/protocol names
(SMTP, STARTTLS, TLS, CPU, Xray, Telegram) are kept as-is.

---------

Co-authored-by: Sanaei <ho3ein.sanaei@gmail.com>

internal/web/entity/entity.go

@@ -39,16 +39,27 @@ type AllSetting struct {
 	Datepicker  string `json:"datepicker" form:"datepicker"`                            // Date picker format
 
 	// Telegram bot settings
-	TgBotEnable      bool   `json:"tgBotEnable" form:"tgBotEnable"`              // Enable Telegram bot notifications
-	TgBotToken       string `json:"tgBotToken" form:"tgBotToken"`                // Telegram bot token
-	TgBotProxy       string `json:"tgBotProxy" form:"tgBotProxy"`                // Proxy URL for Telegram bot
-	TgBotAPIServer   string `json:"tgBotAPIServer" form:"tgBotAPIServer"`        // Custom API server for Telegram bot
-	TgBotChatId      string `json:"tgBotChatId" form:"tgBotChatId"`              // Telegram chat ID for notifications
-	TgRunTime        string `json:"tgRunTime" form:"tgRunTime"`                  // Cron schedule for Telegram notifications
-	TgBotBackup      bool   `json:"tgBotBackup" form:"tgBotBackup"`              // Enable database backup via Telegram
-	TgBotLoginNotify bool   `json:"tgBotLoginNotify" form:"tgBotLoginNotify"`    // Send login notifications
-	TgCpu            int    `json:"tgCpu" form:"tgCpu" validate:"gte=0,lte=100"` // CPU usage threshold for alerts (percent)
-	TgLang           string `json:"tgLang" form:"tgLang"`                        // Telegram bot language
+	TgBotEnable     bool   `json:"tgBotEnable" form:"tgBotEnable"`              // Enable Telegram bot notifications
+	TgBotToken      string `json:"tgBotToken" form:"tgBotToken"`                // Telegram bot token
+	TgBotProxy      string `json:"tgBotProxy" form:"tgBotProxy"`                // Proxy URL for Telegram bot
+	TgBotAPIServer  string `json:"tgBotAPIServer" form:"tgBotAPIServer"`        // Custom API server for Telegram bot
+	TgBotChatId     string `json:"tgBotChatId" form:"tgBotChatId"`              // Telegram chat ID for notifications
+	TgRunTime       string `json:"tgRunTime" form:"tgRunTime"`                  // Cron schedule for Telegram notifications
+	TgBotBackup     bool   `json:"tgBotBackup" form:"tgBotBackup"`              // Enable database backup via Telegram
+	TgCpu           int    `json:"tgCpu" form:"tgCpu" validate:"gte=0,lte=100"` // CPU usage threshold for alerts (percent)
+	TgLang          string `json:"tgLang" form:"tgLang"`                        // Telegram bot language
+	TgEnabledEvents string `json:"tgEnabledEvents" form:"tgEnabledEvents"`      // Comma-separated event types to send via Telegram
+
+	// Email (SMTP) notification settings
+	SmtpEnable         bool   `json:"smtpEnable" form:"smtpEnable"`                        // Enable email notifications
+	SmtpHost           string `json:"smtpHost" form:"smtpHost"`                            // SMTP server host
+	SmtpPort           int    `json:"smtpPort" form:"smtpPort" validate:"gte=1,lte=65535"` // SMTP server port
+	SmtpUsername       string `json:"smtpUsername" form:"smtpUsername"`                    // SMTP username
+	SmtpPassword       string `json:"smtpPassword" form:"smtpPassword"`                    // SMTP password
+	SmtpTo             string `json:"smtpTo" form:"smtpTo"`                                // Comma-separated recipient emails
+	SmtpEncryptionType string `json:"smtpEncryptionType" form:"smtpEncryptionType"`        // SMTP encryption: none, starttls, tls
+	SmtpEnabledEvents  string `json:"smtpEnabledEvents" form:"smtpEnabledEvents"`          // Comma-separated event types to send via email
+	SmtpCpu            int    `json:"smtpCpu" form:"smtpCpu" validate:"gte=0,lte=100"`     // CPU threshold for email notifications
 
 	// Security settings
 	TimeLocation    string `json:"timeLocation" form:"timeLocation"`       // Time zone location
@@ -130,6 +141,7 @@ type AllSettingView struct {
 	HasApiToken       bool `json:"hasApiToken"`
 	HasWarpSecret     bool `json:"hasWarpSecret"`
 	HasNordSecret     bool `json:"hasNordSecret"`
+	HasSmtpPassword   bool `json:"hasSmtpPassword"`
 }
 
 // CheckValid validates all settings in the AllSetting struct, checking IP addresses, ports, SSL certificates, and other configuration values.