Show HN: Typesync, schema-first Firestore tooling that now validates stored data

Hi HN,

I’ve been working on Typesync, an open-source CLI for Firestore projects.

The basic idea is that you define your Firestore models once in YAML or JSON, then generate the boring parts from that:

- TypeScript models - Python/Pydantic models - Swift models - Firestore Security Rules validators - Mermaid diagrams of the document structure

The new command I added is `validate-data`.

It walks selected Firestore collections and validates existing documents against Zod validators generated from the same schema. It reports the documents that don’t match.

Example:

```bash typesync validate-data \ --definition 'definition/*/*.yml' \ --model User \ --model Post \ --serviceAccount ./service-account.json ```