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)

internal/web/controller/api.go

@@ -90,7 +90,6 @@ var nodeSyncScopeAllow = map[string]map[string]struct{}{
 	"/clients/del/:email":          {http.MethodPost: {}},
 	"/clients/:email/detach":       {http.MethodPost: {}},
 	"/clients/update/:email":       {http.MethodPost: {}},
-	"/server/restartXrayService":   {http.MethodPost: {}},
 	"/server/getWebCertFiles":      {http.MethodGet: {}},
 	"/server/descendants":          {http.MethodGet: {}},
 	"/clients/resetTraffic/:email": {http.MethodPost: {}},