Faithful export: whole-path MIDI (the full loop, not the current song)

Paul: "video, audio, and MIDI export … the entire path, not just the current song." First of the three: MIDI.

• makeWalk's per-bar payload now carries `ev` (the note-level buildEvents of that bar's collapsed section).

• midi-export.buildMidiJourney(bars) concatenates the per-bar note events (each offset by its absolute startBeat) into ONE SMF with a tempo map — pads/bass/ melody + GM drums across every genre the loop crosses.

• journey.buildLoopMidi() walks one full loop and assembles it.

• app/export.js downloadMidi now exports the WHOLE PATH when a loop is drawn ("… (full path).mid"), falling back to the current song when there's no path.

Verified: a 3-waypoint loop -> a valid format-1 5-track SMF; explorer-ui's MIDI gate parses it clean.

▶ Play it: Ballroom Leviathan — a horn-and-piano genre that plays almost entirely sampled instruments https://stellate.app/?genre=bigband&seed=6805&path=814.14134,833.14167,795.14167&xdur=13.122

4eaada1 https://github.com/aboard-io/stellate/commit/4eaada1de7a77579b9f3c69f50d7110e0991d5c0