v2.1.57: Citation notes

Citation notes

Citation notes are now displayed instead of being discarded. For example,
\cite[Lemma~7.3, p.~251]{Santambrogio2015} keeps the lemma and page after
the bibliography number. Two optional arguments retain both the prenote and
postnote.

• Notes preserve inline formatting, math, and nonbreaking spaces.
• The same behavior works in headings, captions, tables, and text macros.
• Bibliography links, hover previews, source navigation, and live edits remain
  available with both manual bibliographies and BibTeX entries.
• Empty notes, comments, protected brackets, and half-open math intervals are
  handled without losing the citation link.

Verified with 692 Rust tests and 42 Chromium/WebKit bibliography and figure-sync
checks.

After updating the plugin and binary, run :MathPreviewRestart.

Prebuilt binaries are available for macOS and Linux on arm64 and x86_64, with
SHA-256 checksums for every archive.