aterm 0.71.0

aterm is the terminal for AI. New here? What each file is:

• aterm-0.71.0.dmg — the signed, notarized app as a drag-install DMG (~28 MB). The ALab toolchain installs itself on first launch (or on demand via aterm pkg install --default-set).
• aterm-0.71.0-mac.zip — the same app as a zip (~26 MB); this is the container the in-app updater and Homebrew stage from.
• aterm.dmg / aterm-mac.zip — permanent releases/latest/download/ names for the DMG and the zip above (byte-identical copies).
• .sha256 files verify a download: shasum -a 256 -c <asset>.sha256.
• aterm-appcast.toml / aterm-machines.toml (and their .sig) are consumed by the in-app self-updater — not for humans.
• Releases named atpkg-index-N are machine-readable package indexes, not app releases.

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Changed

• The cursor rainbow is a proper sky rainbow again. It runs red, orange,
  yellow, green, blue, indigo, violet — and between green and blue it passes
  through cyan, because that is what a rainbow does. aterm used to forbid that
  crossing, and the machinery enforcing it could only do so by draining the
  colour out of exactly that part of the arc: the fold it used preserves
  brightness, so what it produced was not a paler blue but a bright grey. That
  grey was most visible in the streak a jumping cursor leaves behind. The
  crossing now keeps its own colour, and the ribbon reads continuously across
  all seven hues — measurably more of them (12 distinct hues on the release
  paint probe, up from 10) at the same brightness.