fix(ui): stub Node built-ins for fixture bundle

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.

e2e/ui/node-stubs.mjs

@@ -0,0 +1,36 @@
+// Stubs for Node.js built-ins used by server-only modules that leak into the
+// UI fixture bundle. These keep esbuild from failing on `node:*` imports
+// while providing shape-compatible exports so the bundle stays loadable.
+
+export class AsyncLocalStorage<T = unknown> {
+	enterWith(): void {}
+	exit(): void {}
+	getStore(): T | undefined {
+		return undefined;
+	}
+	run<U>(store: T, work: () => U): U {
+		return work();
+	}
+}
+
+export function createHash(): { update(): { digest(): string } } {
+	return {
+		update: () => ({
+			digest: () => "",
+		}),
+	};
+}
+
+export function randomUUID(): string {
+	return "00000000-0000-0000-0000-000000000000";
+}
+
+export async function readFile(): Promise<Buffer> {
+	return Buffer.alloc(0);
+}
+
+export const path = {
+	join: (...parts: string[]): string => parts.join("/"),
+	resolve: (...parts: string[]): string => parts.join("/"),
+	sep: "/",
+};