P9(4): remove local-core live-test trio — outbound speed test + egress probe, restart/stop xray endpoints

Per user decision 2026-10-21 (reverses the earlier keep call in
PANEL-LITE-SPEC.md, now amended): the lite panel never runs a local
core, so measuring/probing from the panel host is meaningless.

Backend:
- delete service/outbound probe implementation (probe_http.go and its
  tests) and the TestOutbound/TestOutbounds batch prober; outbound
  traffic accounting (AddTraffic/GetOutboundsTraffic/Reset) unchanged
- drop POST /panel/api/xray/testOutbound + testOutbounds routes and the
  outboundTestUrl setting (get/update plumbing removed; stored rows in
  existing DBs are inert)
- drop POST /panel/api/server/restartXrayService + stopXrayService
  routes/handlers and the node-sync allowlist entry; the service-level
  Stop/RestartXrayService stay for internal import/restore flows
- node-sync allowlist contract test updated to the new inventory

Frontend:
- remove test buttons/mode switch/test-all from outbounds tab, card
  list and table columns; delete TestResultPopover and CountryPill;
  drop the egress/country/latency columns fed by probe results
- remove outboundTestUrl state and save plumbing from useXraySetting
  and the Basics tab field; drop OutboundTestResult schemas
- delete the 15 now-dead i18n keys from all 13 locales (incl. the
  restart/stop keys orphaned since P6/P7 — i18n-dead-keys test green)
- tests: drop the test-URL hook test, re-probe the loopback index
  mapping through Move-to-top, regenerate API types (gen)

PANEL-LITE-SPEC.md

@@ -24,11 +24,12 @@
 - 安全设置：双重验证（2FA，用户不用）
 - 邮件模块（SMTP 发送：到期/流量提醒等，用户不用）
 - 分组功能（客户端归类标签 + 按组批量操作/聚合订阅；用户从未用过，裁功能不影响已建客户端与订阅）
+- 本地核心实测三件套（P9 第 4 条，用户 2026-10-21 晚改口）：出站测速（临时 xray 实例批量探测 `testOutbound(s)` 接口 + 前端测试按钮/模式切换/结果弹层）、出口探测（同一动作的 egress IP/国家展示）、重启/停止核心接口（`restartXrayService`/`stopXrayService`，与首页已摘按钮同族）；出站与路由的模板编辑（增删改存）保留不动
 
 ## 范围确认（2026-10-21 用户拍板：四项全部保留，不裁）
 
 - 协议范围：保留全部协议模板（VLESS、SS2022、VMess、Trojan、WireGuard、TUIC、Hysteria、MTProto 等），不收窄
-- IP 检查 / 测速类后台任务：保留
+- IP 检查 / 测速类后台任务：保留 → **2026-10-21 晚用户改口推翻本项**：出站测速 + 出口探测（同一动作，测的是主控本地网络位置；精简主控不跑本机核心、无本地出站，测速结果无意义）连同重启/停止核心控件与接口，已于 P9 第 4 条摘除。其余三项（协议范围 / ACME / 多用户）保留不变，不要再翻出来问。
 - 面板内置 ACME 签证书：保留
 - 多用户功能：保留
 - 用户理由：这四块以静态代码为主，裁掉省不了多少内存。此节关闭，后续轮次不要再翻出来问。