v0.4.2

• ipm.embedBuffer accepts tokensOnly: true, which returns each block's
  source and tokens without laying out an SVG (110 ms → 35 ms on a
  3234-line, 95-block document; 926 KB → 130 KB). An editor coloring a live
  buffer needs tokens for the text as it stands on this keystroke, while the
  diagram can wait for a pause — this lets a client run the two on separate
  cadences. Every other field is unchanged, and a server that predates the
  flag ignores it and renders in full.
• Every shipping command answers --version, printing <tool> <version> taken
  from the build information the Go toolchain embeds — so a binary unpacked from
  a release archive can say what it is. Previously only ipm-rpc could be asked,
  because it is the one the VS Code extension interrogates; the other six exited
  with flag provided but not defined: -version.
• Note that the provenance stamp md-embed writes into generated SVGs stays
  md-embed@dev and is deliberately not this version: it marks which tool
  produced a diagram, and tying it to the release would put a version bump into
  the diff of every committed SVG.