The drive-half complement to the toast system (D-6 parity, like ui.open):
`clide ui toast "msg" [--severity success|warning|error|info] [--duration MS]`
publishes a message on the kernel MessageBus 'toast' channel, which the
ToastService consumes — so a hosted Claude session or any script can surface
"done/failed" on the user's screen. The channel literal is kept in ui_command
(not imported from the kernel) so the daemon command stays Flutter-free.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>