Hide pages and sections by adding hidden to frontmatter

[bram-dingelstad]

This feature is implemented based on discussion on the forum as well as #2391

Sanity check:

• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Code changes

(Delete or ignore this section for documentation changes)

• Are you doing the PR on the next branch?

If the change is a new feature or adding to/changing an existing one:

• Have you created/updated the relevant documentation page(s)?

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I've added hidden to both PageFrontMatter & SectionFrontMatter and made sure to filter them in the Paginator, which covers my use case.

Work that I can still do to bring this to completion:

• Update documentation
• Make sure it filters out of search index (not sure how to do this, would love pointers)
• Make sure it filters out of any generated feed

Lemme know what y'all think ✨

[bram-dingelstad]

Since hidden is a Option<bool> its good to default to false right? I was thinking of leaving it empty, implying the None state.
I assumed that people would get confused and since the None implies false with the inheritence rules specified above it, it should be fine!

Lemme know

[tuyen-at-work]

Hi @bram-dingelstad,

I'm the initiator of the mentioned GitHub discussion, and I wanted to highlight some potential changes needed to exclude hidden pages from search:

• To exclude hidden sections: at this line, check if the section's hidden property is true (or not false). If it is, return immediately:
  https://github.com/getzola/zola/blob/master/components/search/src/elasticlunr.rs#L110

• To skip hidden pages: At this line, check if the page's hidden property is true (or not false). If it is, skip the current iteration:
  https://github.com/getzola/zola/blob/master/components/search/src/elasticlunr.rs#L131

Additional improvements:

• Exclude section/page from sitemap exclusion: In the sitemap rendering logic, exclude hidden pages to prevent them from being indexed:
  https://github.com/getzola/zola/blob/master/components/site/src/sitemap.rs#L59

• Expose hidden in templates: add the hidden property to these serialization structs, allowing template creators to check it and make necessary changes (e.g., hide pages from navigation or add a noindex meta tag):
  https://github.com/getzola/zola/blob/master/components/content/src/ser.rs#L43
  https://github.com/getzola/zola/blob/master/components/content/src/ser.rs#L142

[bram-dingelstad]

Great suggestions @tuyen-at-work! I'll get to adding those when I have the time!
Thank you so much for taking the time 🙏🏻 ✨