API to update Schema Enforcer JSON Schema

Feature request

Is your feature request related to a problem?

Tracking plans are commonly maintained in internal tools or in products such as Avo.

Being able to automatically push tracking plan schemas from the single-source-of-truth tracking plan into PostHog's Schema Enforcer would allow users to get the full value of Schema Enforcer without having to worry about manually updating the JSON Schemas it uses for validation.

Describe the solution you'd like

An API that accepts a JSON (ideally some form of a JSON Schema) to update the Schema Enforcer would allow users and 3rd party tools to build direct integrations to automate workflows around updating tracking plans/schemas.

Describe alternatives you've considered

Additional context

I'm the co-founder/CTO of Avo, and we already have shared customers asking for a direct publishing integration between Avo's Tracking Plan and the PostHog Schema Enforcer

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]

The issue names no files or tests. Start by locating the Schema Enforcer's existing JSON Schema validation and update entry points, then define the API contract and integration behavior. Done means a documented API accepts a JSON Schema and updates the schemas used for validation.