A start towards partial decorators for better composability

[agriyakhetarpal]

This PR introduces the use of partial decorators, a new feature in Hugo released with v0.154.0: https://github.com/gohugoio/hugo/releases/tag/v0.154.0. This will not be a user-facing change for our users. The documentation is at https://gohugo.io/functions/templates/inner/ and is currently a bit sparse, but still understandable. From the docs: I have bumped to Hugo v0.154.5 with this PR.

A partial decorator is a partial template called from any other template including shortcodes, render hooks, and other partials.

There are some more examples here: gohugoio/hugoDocs#3330. I was able to do this for a couple of partials in this PR. Particularly, we can start using this for the list partial (with and without summary) and for the content container (breadcrumbs and title/subtitle) that occupies space on all pages.

I also tried to add something to deduplicate the grid of items and cards, but that turned out to be more complicated – the content inside needs access to outer variables such as $card and .body. I think we can go ahead with this, for now at least, since it's a net win for easy deduplication either way and we can do this kind of work incrementally.

> [!NOTE]
I'll mark this PR as a draft for a while, as the migration to Hugo 0.152.2 for downstream websites isn't complete yet.

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[stefanv]

I like the direction this is taking 👍

[stefanv]

Also, it's neat that Hugo finally added that feature!

[stefanv]

5:55:50 PM: ERROR error building site: render: [en v1.0.0 guest] failed to render pages: render of "/opt/build/repo/blog/content/posts/community-stories/will_tirone/index.md" failed: "/opt/build/scientific-python-hugo-theme/layouts/posts/single.html:2:3": execute of template failed: template: posts/single.html:2:3: executing "main" at <partial "posts/post.html" .>: error calling partial: "/opt/build/scientific-python-hugo-theme/layouts/partials/posts/post.html:3:10": execute of template failed: template: _partials/posts/post.html:3:10: executing "_partials/posts/post.html" at <partial "_decorators/content-container.html" .>: error calling partial: "/opt/build/scientific-python-hugo-theme/layouts/partials/_decorators/content-container.html:7:6": execute of template failed: template: _partials/_decorators/content-container.html:7:6: executing "_partials/_decorators/content-container.html" at <inner .>: error calling inner: template: _partials/posts/post.html:6:14: executing "_partials/_internal/decorator_8e9d3f7b5767b258" at <$featuredImage>: undefined variable: $featuredImage