Typesense search index issues

[sammeltassen]

Gathering some issues around the search index:

• Article illustrations are now indexed as well; they shouldn't be, or only as part of articles.
• Deleted manifests persist in the search index and need to be removed manually. Can they be removed from the search index upon build?
• Bilingual articles are indexed twice, but they link to the same article when appearing in the search results (the link follows the current language setting). It would be better to show only the result of the current language setting (which would require adding the language as a search facet). Downside is that articles available in a single language would not show up (and most of the IIIF content is Dutch only). Alternative is to add bilingual articles as a single entry to the index (and change the title on the results page according to the current language setting).