[Exeloo]

What does this PR do?

No linked issue: this is a full audit of the loader pages, requested directly. They are cut down to what an nf start/nf dev user acts on: what runs where, ports, env, HTTPS and the secure context, cache, loading steps, the main() arguments, and troubleshooting. The npx and standalone usage is removed, and the pages link to the CLI pages instead of repeating them. Slugs are unchanged.

These pages describe loader main, including the per-file cache that came after 1.6.0. They go live with the next loader release, which this matches.

How do you test this PR?

• Before: the pages gave a default for -d (there is none), focused on npx, and showed a .env name the client never gets.
• After: the pages match apps/*. The server loader's crash behaviour was reproduced on 1.6.0: it exits even with --watch.
• docs-sync check, then mint validate, mint broken-links and mint a11y on a scratch copy of the site with all four source branches (engine, cli, loader, editor) and the docs redirects synced in: all pass, 83 pages.
• pnpm exec prettier --check and the pre-push hook (lint, tests): pass.

Merge danger

Door: two-way, docs only: a revert is enough.
Blast radius: the public docs.nanoforge.eu, at this repo's next release (docs-sync), not at merge.

Follow-up issues

To be filed: the server loader exits when the game crashes in --watch mode; the loading page has <title>Title</title>.

Quality gate

Lane	Result
Docs	the change is docs
Correctness	independent reviewer: findings fixed in the last commit
Accessibility (content)	pass (alt text, headings, link text; mint a11y)
Security (content)	pass, no secrets or internal URLs
Style	style-reviewer: pass
Performance	N/A (docs)