templates/docs: Layout.astro 404s the chrome stylesheet on first build
## What happened
Lifted `templates/docs/` wholesale into `gitlab-com/public-sector/kaniko`, ran the documented placeholder pass, started the dev server. `site/src/layouts/Layout.astro` links the chrome stylesheet at:
```
${import.meta.env.BASE_URL}design/chrome/docs/index.css
```
That resolves to a path under the consumer's local Pages base (e.g. `/public-sector/kaniko/design/chrome/docs/index.css`). The template ships no corresponding `site/public/design/` subtree, so the stylesheet 404s on every consumer until they vendor it manually.
## What you expected to happen
A first build off the template renders with the Public Sector chrome applied. Either the template ships the vendored design subtree, ships a sync target, or links the CDN URL directly.
## Related drifts
- `README-template.md` references `site/src/styles/global.css` as a placeholder-bearing file, but the template doesn't ship that file.
- No `make sync-design` target or README instruction on how to populate `site/public/design/`.
## Suggested fix
Lightest path: change `Layout.astro` to link the reference's Pages CDN directly (matches `standards/design/SKILL.md` bullet 1):
```html
<link rel="stylesheet" href="https://gitlab-com.gitlab.io/public-sector/reference/design/chrome/docs/index.css" />
```
Consumers who need airgap or commit-pinned chrome vendor and patch the link.
## Environment
- Reference version: f353b99 (post-v1.1.0)
- Consumer: gitlab.com/gitlab-com/public-sector/kaniko
- Workaround applied: changed link to CDN URL
## Assessed impact
- [x] Template renders wrong
issue