feat(astro): Directus content collections

This PR brings changes that implement Astro content collections on top of the models provided by a Directus SDK client.

Adds

• @astropub/md (<Markdown />,markdown())
• a Directus GraphQL client inspired by palmiak/pacamara-astro-directus
• a decrypt script
• an initial tsconfig.json
• an initial CUBE CSS scaffold

Modifies

• Upgrades the project and with it Astro to ^3.0.0 for @astrojs/markdown-remark used in @astropub/md

Removes

• src/content/
• src/utils/api.ts
• @resilien/directus-to-markdown

Misses

• Content Collection functionalities

Closes #9 (closed)