feat(demo): replace porcelain CLI reference with muse midi semantic porcelain commands (#114)

Replace the 12 generic VCS commands with all 11 muse midi Tier 3 semantic porcelain commands: notes, note-log, note-blame, harmony, piano-roll, hotspots, velocity-profile, transpose, mix, query, check. Flags and return values sourced directly from the command implementations. Update section heading to 'muse midi — Semantic Porcelain Commands'.

Co-authored-by: Gabriel Cardona <gabriel@tellurstori.com>