Casso 1.23.1

Added

• The release zip carries four demo disks under Apple2\Demos, where the
  disk picker already looks: casso-rocks, the hi-res and double hi-res
  Mockingboard speech demos, and the Mockingboard tone demo.
• SHA256SUMS.txt ships with each release, covering both zips in the
  format sha256sum -c reads.
• Casso publishes to winget as relmer.Casso.

Changed

• Release binaries are signed with Azure Artifact Signing, so Windows stops
  warning about an unknown publisher. A build with no signing secrets ships
  unsigned with a warning rather than failing.

Fixed

• A fresh install came up in color, then switched to green on the second
  launch. The default color mode is the phosphor of the monitor the machine
  ships with, but the boot path skipped it for a machine with nothing saved
  yet.
• Opening Settings and changing anything knocked the picture out of green.
  The sheet read an unsaved color mode as Color rather than as the monitor's,
  and OK applied that back onto the running machine.
• Ctrl+0 reset the monitor's tilt without saving the reset, so the bezel
  came back tilted at the next launch.