content/pipeline:
x helper to index based on a search query
- parallelize SIM indexing

UI/UX fixes:
x all links in new tabs
x "keyword" in front-page box; replace identifier with examples
x default to "availability: fulltext"
x update front-page thumb selection (-1 PLOS)
x brief user guide
x "indexed" -> "json" (tag)
x fatcat tag with link; "metadata"?
x OA facet broken; needs tagging?
x vertical alignment of thumbnails
x pagination
x filter HTML form weirdness
    => split off "hidden" form fields
x textpipe to escape HTML better
    => regression test
x group pages within issues
x container links broken?
x tag/tags
x color+link OA tags. or click to filter?
- better labeling pre-prints

cleanups:
x make fmt -> black
x flake8
x mypy require annotations?

ponder:
x single paragraph on front page
x "This fulltext search index includes over 25 million research articles and other scholarly documents preserved in the Internet Archive."
- some space-holder for missing thumbnails
- smaller author font size
- "search inside" phrasing

data quality:
- handle sim_issue items with multiple issues in single item (eg, issue="3-4")