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>

firmware/drivers/pots.h

@@ -0,0 +1,12 @@
+/* ENERGY on ADC0 (GP26), DRIFT on ADC1 (GP27). Averaged, then 7-bit with hysteresis. */
+#ifndef SEEDBOX_POTS_H
+#define SEEDBOX_POTS_H
+
+enum { POT_ENERGY = 0, POT_DRIFT = 1 };
+
+void pots_init(void);
+void pots_update(void);      /* call every few ms */
+int  pot_value(int pot);     /* 0..127 */
+int  pot_raw(int pot);       /* last averaged 12-bit reading, for the bench */
+
+#endif