openalexConvert 0.1.1

• License changed from GPL (>= 2) to MIT.
• corpus_to_csljson() wrote every item's publication date as an empty "issued": {"date-parts": []}: the internal sanitizer only kept named list elements, so the unnamed date-parts list was emptied. All dates were lost in the CSL JSON and in everything converted from it (BibTeX/BibLaTeX had no usable year, citations showed "n.d."). Dates are now written.
• corpus_to_csljson() treated a missing (NA) ISBN or ISSN-L as present, because nzchar(NA) is TRUE. As a result every book and preprint was written as article-journal, and the ISSN never fell back to the work's list of ISSNs when the ISSN-L was missing. Books now stay book, preprints become manuscript, and the ISSN fallback works.
• corpus_to_csljson() wrote OA_status:NA into the note (and so into Zotero's Extra field) for works without an open-access status. A missing status is now left out.
• csljson_to_zotero(): when Zotero refused to create a collection or to grant write access with a plain-text error (e.g. Forbidden), the response was parsed as JSON before its status was checked, so the user saw an unhelpful jsonlite "lexical error" instead of the intended message. The status is now checked first.