move old chronas ui to old.chronas.org and replace chronas.org with the new chronas front

[aumanjoa]

Overview

The new Chronas frontend (new.chronas.org) is now stable enough to become the primary site. This issue covers all the infrastructure and content changes needed to promote the new frontend to chronas.org while preserving access to the old frontend under old.chronas.org.

Tasks

1. DNS / Hosting changes

• Point chronas.org to the new frontend (currently at new.chronas.org)
• Move the old Chronas frontend to old.chronas.org and confirm it loads correctly there
• Verify SSL certificates are valid for both chronas.org and old.chronas.org after the DNS switch
• Confirm CDN / caching rules are updated so both domains serve the correct frontend

2. Banner updates

New frontend (chronas.org after switch):

• Update the top banner to reflect that this is now the main/default Chronas
• Replace or remove the "Try the new Chronas" messaging (no longer relevant)
• Add a banner or footer link pointing users to old.chronas.org if they want the classic interface
• Keep the GitHub issues link visible and prominent in the banner

Old frontend (old.chronas.org):

• Update the banner on the old frontend to say it is the legacy/classic version
• Add a clear link to the new frontend at chronas.org
• Keep the GitHub issues link visible

3. Old frontend cross-linking

• On old.chronas.org, add a visible link/button that directs users to the new frontend at chronas.org
• Ensure any existing "Try new Chronas" links on the old frontend point to chronas.org (not new.chronas.org) after the switch

4. Language subdomain investigation

• Audit all [language].chronas.org subdomains (e.g. de.chronas.org, fr.chronas.org, etc.)
• Determine which subdomains are active and what they currently serve
• Ensure each language subdomain either points to the new frontend or is redirected appropriately
• Verify that translation/i18n loading works correctly on the new frontend for all supported locales
• Update DNS entries for any language subdomains that need to be pointed to the new frontend

Acceptance Criteria

• chronas.org serves the new frontend
• old.chronas.org serves the old/legacy frontend
• Both sites are accessible over HTTPS with valid certificates
• The new site's banner no longer says "new" or references new.chronas.org
• The old site's banner links back to the new chronas.org
• All language subdomains are audited and serve correct content
• No broken links between the two frontends