Updated the local nextcloud tutorial for better use for non technical persons

[remko48]

tutorial: expand local Nextcloud tutorial for non-technical users

Summary

• Rewrote the "Nextcloud lokaal draaien" tutorial (NL) to be accessible to users with no prior terminal or Docker experience, expanding from ~15 min to ~30 min estimated reading time.
• Added OS-aware tab sections (<OSTabs>) that auto-detect Windows, Mac, or Linux and show step-by-step instructions tailored to each platform — including how to open a terminal, install WSL 2, and install Docker Desktop.
• Added a Troubleshooting section and a prominent disclaimer that this is a local dev environment, not for real/sensitive data.
• Added npm run preview script to package.json for a one-command production build preview.
• Fixed inline <code> vertical alignment in site.css so inline code no longer drops below the surrounding text baseline.

[WilcoLouwerse]

🟡 Missing PR description

This PR makes non-trivial changes (816 additions across 4 files) but has no description. The title is descriptive, but a short description covering:

• What changed and why (e.g. "rewrite for non-technical audience — adds OS-tabbed instructions, fleshes out Step 0, adds Troubleshooting component")
• Notable behavioral additions (e.g. OSTabs UA-detection component, Client Push rename, preview npm script)
• Anything reviewers should know that is not obvious from the diff

…makes future maintainers (and the GitHub release notes generator) far happier. Not a blocker — review continues with APPROVE.

[WilcoLouwerse]

Inline observations — see verdict below.

[WilcoLouwerse]

No blockers — friendly, well-paced rewrite for a non-technical audience. Worth addressing before merge: Dutch typo virtuale → virtuele and a missing PR description. Three minor polish notes on the side: <OSTabs> SSR default hardcodes Windows, Windows notepad code block has no language hint, and notify_push is named once in prose before being relabelled to Client Push which may confuse beginners.

[WilcoLouwerse]

Re-review: all 4 prior threads resolved by the author and the new commit (61a1fe9 Added requested changes) addresses each one — Dutch typo virtuale → virtuele fixed, OSTabs rewritten with a lazy useState initializer that reads localStorage / UA on first render (different from the suggested <BrowserOnly> approach but resolves the user-visible flicker), notify_push now clarified inline as also known as Client Push in the Nextcloud app store, and the notepad docker-compose.yml block gained a bash fence. The full PR description was also added.

One sub-item from the original 🟢 fence-consistency note remains: the http://localhost:8080 URL block at line 281 (English + Dutch mirror) is still a bare ```` fence. Cosmetic only — URL blocks don't benefit from syntax highlighting — so not worth blocking on. Optional follow-up if you happen to touch the file again.

CI: 5 success / 1 skipped / 0 failing. Nice work on the non-technical rewrite.