feat(sidebar): move Routing/Outbounds to top-level items with clean URLs

- Move Routing out of the Xray Configs submenu; add Routing and Outbounds
  as top-level sidebar items below Hosts
- Give them their own clean routes (/routing, /outbound) instead of
  /xray#routing and /xray#outbound, registered in the React router and the
  Go SPA shell so direct links and refresh work
- XrayPage derives the active section from the pathname for those routes
- Add menu.routing and menu.outbounds translation keys across all locales

frontend/src/hooks/usePageTitle.ts

@@ -10,6 +10,8 @@ const TITLE_KEYS: Record<string, string> = {
   '/nodes': 'menu.nodes',
   '/settings': 'menu.settings',
   '/xray': 'menu.xray',
+  '/outbound': 'menu.outbounds',
+  '/routing': 'menu.routing',
   '/api-docs': 'menu.apiDocs',
 };