Metadata at chapter level for Quarto books: store and render

[christofs]

We used Quarto in a recent book project and loved it! However, in this book, different chapters were written by different people, and as a consequence, we missed a feature to store and render chapter-level metadata:

(1) Store chapter-level metadata in each .(q)md file, for example in a yaml header.

1. In particular author, title, URL
2. However, book title, editors, publisher, year etc. also need to be available

(2) Allow rendering that metadata in one or several of the following forms:

1. In HTML and/or PDF output, as a citation suggestion in a specified location rendered to a string according to a specified citation style defined in a CSL file, for consumption by human readers;
2. In HTML output, render into the HTML meta tags, in the HTML head, for consumption by reference managers like Zotero or Citavi.
3. In HTML output, as a BibTeX snippet, optionally hidden behind a copy/paste button, for copying into reference managers that don't read meta tags.

In our last book project, we did implement these things by hand after rendering, but it is of course error-prone and breaks the beauty of one-click rendering.

For a working example, see our resulting book here: https://methods.clsinfra.io/general-intro.html