Improve package metadata validation

[kmturley]

Currently package metadata is committed to git as freely-typed yaml files.
When the Registry is built, Yaml files are converted to JSON and checked with some custom validation logic:
https://github.com/open-audio-stack/open-audio-stack-core/blob/main/src/helpers/package.ts#L86

Things to validate:

• Field names are correct
• Required fields are populated
• Values are valid type
• Values are valid values
• Values length, formatting

Essentially it means coming up with a custom validation library, which requires lots of effort and could miss validations and/or contain bugs.

Instead of spending more time on custom validation logic, instead use a validation library which will do it automatically.
JSON schema is one obvious option, but it requires a lot of work to define the JSON schema files. JavaScript does not contain enough information for proper validation, but TypeScript does.

Recommendation to use Zod

Zod is a TypeScript-first schema declaration and validation library. With Zod, you declare a validator once and Zod will automatically infer the static TypeScript type

https://github.com/colinhacks/zod

This allows validators to be defined in TypeScript, which can be used for both Types and for Validations. Reducing the amount of code required.