fix: prevent site storybook tests from hanging after completion (#23936)

The vitest process hung after all 2132 story tests passed because
leftover refetchInterval polls kept the Node.js event loop alive.
Components that set per-query refetchInterval override the
QueryClient default, causing HTTP requests through vite's proxy
to localhost:3000 (no backend) that never resolve cleanly.

Three fixes:

- preview.tsx: disable all automatic refetching defaults and cancel
  in-flight queries on story unmount via useEffect cleanup
- storybook.tsx: save/restore the original window.WebSocket in the
  withWebSocket decorator, clear pending timers in close()
- vite.config.mts: add explicit testTimeout, hookTimeout, bail, and
  retry settings to the storybook vitest project

Also fix 5 story files that imported from @testing-library/react
instead of storybook/test.

site/scripts/warmup-storybook-cache.mjs

@@ -0,0 +1,27 @@
+// Warm vite's transform cache for storybook story files.
+// Only needed on cold cache (first run after pnpm install).
+import { createServer } from "vite";
+import { readdirSync } from "node:fs";
+import { join, dirname } from "node:path";
+import { fileURLToPath } from "node:url";
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+const root = join(__dirname, "..");
+
+const server = await createServer({
+	configFile: join(root, "vite.config.mts"),
+	root,
+});
+await server.listen();
+
+const stories = readdirSync(join(root, "src"), { recursive: true })
+	.filter((f) => String(f).endsWith(".stories.tsx"))
+	.map((f) => `/src/${f}`);
+
+await Promise.all(
+	stories.map((f) =>
+		server.environments.client.warmupRequest(f).catch(() => {}),
+	),
+);
+
+await server.close();