feat: replace panel proxy URL with outbound-based egress bridge

Instead of requiring a manual SOCKS5/HTTP URL, the panel now lets the
admin pick an Xray outbound from a dropdown (same UX as Geodata
Auto-Update). At runtime, injectPanelEgress appends a loopback SOCKS
inbound (tag: panel-egress) and prepends a routing rule so the panel's
own HTTP traffic — version checks, Telegram, normal geo-file updates —
is routed through the chosen outbound. Xray-native Geodata Auto-Update
is unaffected (it uses its own geodata.outbound inside Xray). Blackhole
outbounds are excluded from both picker dropdowns since routing any
download through one just drops it. Translations updated for all 13
locales.

internal/web/controller/setting.go

@@ -5,6 +5,7 @@ import (
 	"strconv"
 	"time"
 
+	"github.com/mhsanaei/3x-ui/v3/internal/logger"
 	"github.com/mhsanaei/3x-ui/v3/internal/util/crypto"
 	"github.com/mhsanaei/3x-ui/v3/internal/web/entity"
 	"github.com/mhsanaei/3x-ui/v3/internal/web/middleware"
@@ -29,6 +30,7 @@ type SettingController struct {
 	userService     panel.UserService
 	panelService    panel.PanelService
 	apiTokenService panel.ApiTokenService
+	xrayService     service.XrayService
 }
 
 // NewSettingController creates a new SettingController and initializes its routes.
@@ -81,12 +83,21 @@ func (a *SettingController) updateSetting(c *gin.Context) {
 		return
 	}
 	oldTwoFactor, twoFactorErr := a.settingService.GetTwoFactorEnable()
+	oldPanelOutbound, _ := a.settingService.GetPanelOutbound()
 	err := a.settingService.UpdateAllSetting(allSetting)
 	if err == nil && twoFactorErr == nil && !oldTwoFactor && allSetting.TwoFactorEnable {
 		if bumpErr := a.userService.BumpLoginEpoch(); bumpErr != nil {
 			err = bumpErr
 		}
 	}
+	if err == nil && allSetting.PanelOutbound != oldPanelOutbound {
+		// The egress bridge lives in the generated config; reconcile the
+		// running core. One SOCKS inbound plus one routing rule — both
+		// hot-appliable, so this normally does not restart Xray.
+		if applyErr := a.xrayService.RestartXray(false); applyErr != nil {
+			logger.Warning("apply panel outbound change failed:", applyErr)
+		}
+	}
 	jsonMsg(c, I18nWeb(c, "pages.settings.toasts.modifySettings"), err)
 }