Seedbox v0.1 + firmware, generic kit/synth, ROOT/SCALE pages

First commit of the repo. Contents beyond the v0.1 simulator and layout:

- Full Pico 2 W firmware (firmware/app, drivers, engine port, host test).
- BANK page and 404 mode A/B removed; learned pads play exactly what was learned.
- 404/MiniFreak renamed to KIT/SYNTH throughout (jacks, code, sim, docs,
  layout labels; wiring rebuilt).
- ROLL returns to page select after a re-roll; a freshly learned track turns on.
- LCD contrast 66.
- ROOT and SCALE pages: 21 scales, AUTO = the seed picks; global and sticky.

Intended music change: the scale table grew from 8 to 21 and AUTO picks from
all of them, so every seed's scale changed. Vectors regenerated with
npm run vectors, plus new key-override cases. Flash record is now version 2.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tools/build-wiring.js

@@ -0,0 +1,6 @@
+/* Rebuilds tools/wiring.html from tools/wiring-src/* and hardware/layout.js (the one source of truth).
+   Run after editing the layout:  node hardware/check-layout.js && node tools/build-wiring.js */
+var fs=require('fs'), path=require('path'), d=__dirname;
+function rd(p){ return fs.readFileSync(path.join(d,p),'utf8'); }
+var html=rd('wiring-src/head.html')+rd('wiring-src/body.html')+'<script>\n'+rd('../hardware/layout.js')+'\n</script><script>'+rd('wiring-src/render.js')+'</script>';
+fs.writeFileSync(path.join(d,'wiring.html'),html); console.log('wrote tools/wiring.html',html.length,'bytes');