Survey config code editing in dashboard

Feature request

Is your feature request related to a problem?

Editing/creating surveys in the dashboard is a laborious process, especially if you have multiple questions that have the same multiple choice options, since there is no way to duplicate questions and the question accordion only allows 1 open at a time.

Describe the solution you'd like

I'd like to just be able to edit the survey config in-code, that way I can copy/paste questions and have quick access to all the question settings without having to jump back and forth between collapsing accordions.

Describe alternatives you've considered

I've considered just vibe coding a local front end where I can edit them and push updates via the posthog backend api, but that honestly seems like more work than just taking a while to edit this one long survey and be done with it.

Debug info

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

Start by tracing the dashboard's survey creation and editing flow, then read how survey configuration is represented and persisted. Compare the current accordion-based editor with the requested in-code editing experience and identify the relevant API boundary. Done means users can edit or create survey configuration efficiently in the dashboard, including reusing repeated question options.