Get all 4TU.ResearchData links: real hyperlinks from the paper's own url
table, plus a body-text fallback for a BARE mention (a DOI like
"10.4121/16766929" is routinely cited without any URL scheme at all) that
the source PDF/HTML never encoded as an actual hyperlink – the url table
only ever contains links the source document itself made clickable. Same
two-tier approach zenodo_links() uses.
Examples
paper <- demopaper()
researchdata4tu_links(paper)
#> # A tibble: 0 × 6
#> # ℹ 6 variables: href <chr>, link_text <chr>, text_id <int>, paper_id <chr>,
#> # researchdata4tu_url <chr>, researchdata4tu_id <chr>