Updating snapshot tests is impossible per Developing locally

Bug description

The Developing locally guide's section Testing - Frontend is incorrect/outdated and makes it impossible to update snapshots.

The guide mentions:

To update all visual regression test snapshots, make sure Storybook is running on your machine (you can start it with pnpm storybook in a separate Terminal tab).

Trying to update snapshots with Storybook in dev mode as proposed will fail with a timeout with no obvious reason. This is due to the hot module replacement (HMR) running in the background, preventing await page.waitForLoadState('networkidle'); from succeeding, causing the timeout.

Looking at the .github/workflows/storybook-chromatic.yml file, the right way is to:

pnpm install http-server
pnpm run build-storybook
pnpm exec http-server storybook-static --port 6006 

One way to fix this would be to include the above instructions in the guide. Although this would add additional complexity to the instructions. It might be worth extracting the commands into a package.json script and reuse it in both the guide and the workflow.

How to reproduce

1. Prepare the app as per Developing locally
2. Start storybook in one terminal: pnpm storybook
3. Run visual tests in another terminal: pnpm test:visual

Expected: tests pass
Actual: tests fail due to a timeout
Note that this happens only for chromium, not webkit.

Additional context

• Tested on Ubuntu 24.04
• related issue on storybookjs/test-runner

Debug info

- [ ] PostHog Cloud, Debug information: [please copy/paste from https://us.posthog.com/settings/project-details#variables or https://eu.posthog.com/settings/project-details#variables]
- [x] PostHog Hobby self-hosted with `docker compose`, version/commit: a2dc60846d904de647eb4c54624cae0ce7bca530
- [ ] PostHog self-hosted with Kubernetes (deprecated, see [`Sunsetting Kubernetes support`](https://posthog.com/blog/sunsetting-helm-support-posthog)), version/commit: [please provide]

Start with the Testing - Frontend section of the Developing locally guide and compare its commands with .github/workflows/storybook-chromatic.yml. Reproduce the timeout with pnpm storybook and pnpm test:visual, then verify the guide documents a working snapshot-update flow and any shared package.json or workflow instructions remain consistent.