Support page-scoped assets without forcing route changes

[tormnator]

Is your feature request or improvement related to a problem?

Nue's asset loading is currently directory-scoped, which works well for shared area assets, but it makes a common parent-page and child-pages structure awkward.

Example:

• /blog/ has CSS shared by the blog area
• /blog/ also has CSS that should be private to the blog home page
• /blog/posts/* has CSS private to post pages

Today, the blog-home-private CSS tends to flow into descendant pages unless the user reaches for include/exclude, manual <link> tags, or changes the route shape.

Users should not have to change URLs or folder structure just to get page-private assets.

Solution you'd like

A first-class way to scope assets to a single page while preserving clean file-based routes.

The most intuitive option to me is companion page files. For example:

• index.md + index.css
• about.html + about.css

That feels natural, easy to teach, and friendly to rapid development.

Alternatives you've considered

• Generalize the special home/ idea to nested apps, possibly with a name like @home so it does not collide with a literal home/ route segment.
• Add an explicit opt-in config in app.yaml, for example under design, to mark certain files as page-scoped.
• Keep relying on include/exclude or manual head links, but those feel more like workarounds than a first-class solution.

Additional context

I am not attached to one exact implementation. The main goal is to support a very common pattern:

• shared assets for a parent area
• private assets for the parent page
• private assets for child pages

without forcing different URLs or extra routing ceremony.