external_url pages not redirecting to external site

[dannon]

Description

News and event items with external_url frontmatter are not redirecting to the external URL. Instead, they render an empty page on the hub.

Example

https://github.com/galaxyproject/galaxy-hub/blob/master/content/news/2025-09-25-embl-erga/index.md

This news item has:

external_url: https://www.erga-biodiversity.eu/post/erga-at-the-embo-course-in-genome-sequencing-assembly-curation-and-downstream-analyses

In Gridsome, clicking on this news item redirects to the external URL. In Astro, it renders the page without content.

Fix needed

The Astro pages (src/pages/news/[...slug].astro, src/pages/events/[...slug].astro) need to:

1. Check if external_url is set in the article/event data
2. If so, return a redirect response to that URL instead of rendering the page

May also need to ensure external_url is in the articles schema (currently only in events schema).

Reported by: Bjoern