feat(outbound): add real-delay connection test mode

The HTTP probe reports the warm per-request round-trip, which reads
lower than the delay figure client apps show for the same server. Add a
third "real" test mode that reuses the temp-instance HTTP probe but
reports the cold request's full elapsed time - tunnel establishment
included - and skips the warm request. UDP-transport outbounds forced
out of the TCP lane still report "http"; in real mode they report
"real". The mode joins the TCP/HTTP toggle on the outbounds tab, with
the label translated in all 13 locales.

internal/web/translation/zh-TW.json

@@ -1627,7 +1627,8 @@
         "testSuccess": "測試成功",
         "testFailed": "測試失敗",
         "testError": "測試出站失敗",
-        "testModeTooltip": "TCP: 快速 dial-only 探測。HTTP: 透過 xray 的完整請求。",
+        "modeRealDelay": "真實延遲",
+        "testModeTooltip": "TCP: 快速 dial-only 探測。HTTP: 透過 xray 的完整請求。真實延遲: 含建立連線的總耗時。",
         "testAll": "全部測試",
         "httpStatus": "HTTP 狀態",
         "breakdownConnect": "代理連線",