chore(ui): hide Mesh, Fleet Secrets, and Host Console behind experimental discovery (#1624)

Gate Routing, Secrets, Host Console, and Mesh dashboard/settings surfaces on the existing useExperimental readiness flag so immature operator surfaces stay out of the default UI while paid and admin backend gates remain unchanged.

frontend/src/components/EditorLayout/hooks/useUrlSync.test.ts

@@ -26,6 +26,8 @@ function makeReachCtx(over: Partial<ReachabilityContext> = {}): ReachabilityCont
     containerLabelsEnabled: true,
     permissionsStatus: 'ready',
     licenseStatus: 'ready',
+    experimental: true,
+    experimentalReady: true,
     ...over,
   };
 }