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-CN.json

@@ -1627,7 +1627,8 @@
         "testSuccess": "测试成功",
         "testFailed": "测试失败",
         "testError": "测试出站失败",
-        "testModeTooltip": "TCP: 快速 dial-only 探测。HTTP: 通过 xray 的完整请求。",
+        "modeRealDelay": "真实延迟",
+        "testModeTooltip": "TCP: 快速 dial-only 探测。HTTP: 通过 xray 的完整请求。真实延迟: 含建立连接的总耗时。",
         "testAll": "全部测试",
         "httpStatus": "HTTP 状态",
         "breakdownConnect": "代理连接",