Replace platform: 'node' (incompatible with iife browser bundle) with
explicit aliases for node:async_hooks, node:crypto, node:fs/promises,
node:path pointing at e2e/ui/node-stubs.mjs. Provides shape-compatible
exports so esbuild can bundle the UI fixture without failing on Node
built-ins. Increase webServer timeout to 120s for reliable startup.
Add platform: 'node' to esbuild build options so Node.js built-ins
(node:async_hooks, node:crypto, node:fs/promises, node:path) are
treated as external instead of failing to resolve during browser
bundle generation in e2e/ui/fixture-server.mjs.