The old nav used bare lowercase slugs and leaned on filesystem order for
every sidebar.
- Replace the three existing nav entries with six labelled ones, keyed
through i18n.json so both locales resolve to their own text from
identical _nav.json files.
- Add _meta.json for blogs and opensource-projects, grouping entries by
topic instead of leaving them alphabetical.
- Rename the Blogs and Notifications pages so their titles match the nav
labels (Insights and News).
- Point the notification page's account-settings link at GitHub, as the
Gitea instance it referenced is retired.
Frees /products/ for the product page and makes the open-source archive
explicit, rather than leaving two sections that both look like "projects".
- Move the directory in both locales and update the 18 internal links
pointing into it.
- Rework helix for the GitHub layout: server/ and web/ are directories in
a single repository there, not the two separate repositories Gitea had.
The "fork both repositories" step and the section wording follow.
- Correct helix's stated Java version to 21, which is what the build
actually targets.