Generate Open Graph images for Astro files

[julien-deramond]

Prerequisites

• I have searched for duplicate or closed feature requests
• I have read the contributing guidelines

Proposal

Right now, Open Graph images are generated only for what's contained within /src/content. It means that all the Astro pages in src/pages have static images created manually via a Figma template (see https://github.com/Open-reSource/openresource.dev/pull/289/files).

The idea would be to do the exact same thing for src/content but with Astro pages.

Motivation and context

The main motivation is to provide easier maintenance. If a new page is created or that the title or description of an existing page is modified, the image must be recreated manually.