feat: Add integrated blog with RSS and legacy redirects

[flemzord]

Summary

• add internal blog CRUD with draft handling and a public RSS feed at /blog.rss
• import legacy PluXML articles/media with preserved authors and legacy ids
• add permanent redirects for the old blog domain and feed endpoints

Testing

• docker compose run --rm web bundle exec rake blog:import
• docker compose run --rm web bash -lc "bundle install && bundle exec rails runner 'app = ActionDispatch::Integration::Session.new(Rails.application); app.host! \"localhost\"; app.get(\"/blog.rss\"); puts app.response.status'"

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Summary by cubic

Integrated a first-party blog with admin publishing, an RSS feed at /blog.rss, and permanent redirects from the legacy blog domain. Also added a one-shot importer to bring over PluXML articles and media with author mapping and preserved URLs.

• New Features

  • Admin-only CRUD for blog posts with draft/scheduled support and slug generation.
  • Public pages at /blog (paginated) and /blog/:slug; RSS serves the 50 latest published posts.
  • PluXML import via rake blog:import; copies media to /public/data/medias, maps authors, keeps legacy identifiers.
  • Legacy redirects: blog.journalduhacker.net root to /blog, /feed.php to /blog.rss, and article URLs to the matching post.
  • UI: “Blog” link in the nav and status badges; added long date formats in locales.

• Migration

  • Ensure an admin user exists.
  • Put the PluXML export under tmp/blog/articles and tmp/blog/medias.
  • Run: rake blog:import.
  • Verify the feed: GET /blog.rss.
  • Point the legacy blog domain to the app to enable 301 redirects.