fix(ui): esbuild platform node for UI fixture bundling

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.

e2e/ui/fixture-server.mjs

@@ -30,6 +30,7 @@ const bundle = await build({
 	outdir: path.join(root, "test-results/ui-fixture"),
 	format: "iife",
 	jsx: "automatic",
+	platform: "node",
 	alias: { "@": path.join(root, "src") },
 	define: { "process.env.NODE_ENV": '"production"' },
 	plugins: [