Harden worker federation and operator UI

web/vite.config.ts

@@ -2,6 +2,8 @@ import { defineConfig } from 'vite'
 import react from '@vitejs/plugin-react'
 export default defineConfig({
   plugins:[react()],
-  build:{outDir:'dist', emptyOutDir:true},
+  // The Go API embeds this directory. Building anywhere else makes it easy
+  // to test fresh browser sources while deploying a stale embedded bundle.
+  build:{outDir:'../internal/webui/assets', emptyOutDir:true},
   test:{exclude:['**/node_modules/**','**/.node_modules/**','**/dist/**']},
 })