Frontmatter fields
frontmatterFields(z) returns the fields JAAMD sites share, as a plain object
to spread into a content collection schema: title, description, draft,
keywords, author, ogImage and lastUpdated.
// src/content.config.ts
import { frontmatterFields } from '@jaamd/astro/frontmatter'
import { z } from 'astro/zod'
const schema = z.object({
...frontmatterFields(z),
order: z.number().int().optional(),
})