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>

docs/hardware/panel.md

@@ -0,0 +1,46 @@
+# Panel
+
+Landscape layout for a plastic enclosure of about 80 × 150 × 40 mm. The interactive tool (`tools/panel.html`) takes your box size and hole diameters and redraws this, with a fit check.
+
+![Panel layout, landscape](svg/panel-landscape.svg)
+
+- **Left zone**: the screen (on top of the lid), with the encoder and RUN under it.
+- **Middle zone**: ENERGY, DRIFT and SEED.
+- **Right zone**: the 4 × 3 block, in the same order as the screen map: 11 track buttons, with the RUN toggle in the top-right corner. Check at test fit that the toggle's body clears the OUT SYNTH jack behind it on the back wall.
+- **Back wall**: the USB slot for the Pico, and three 3.5 mm MIDI jacks (IN, OUT KIT, OUT SYNTH).
+
+## Inside the box
+
+- **Stripboard**: it lies on the floor with its top edge (strip A) against the back wall.
+- **USB**: the Pico's micro-USB socket ends up about 41 mm from the board's left edge and about 16 mm above the *inside* floor. That stack is foam tape ~1, board 1.6, female header 8.5, the Pico's header spacer 2.5, Pico 1, half the socket ~1.4. Measure your own before cutting the slot.
+- **Slot size**: cut it big enough for the plug's moulding (about 12 × 8 mm), not just the metal tip. The plug has to reach the socket through the wall's thickness.
+- **Fit**: the board is 71 mm front to back, which fits the box's inside depth with a little to spare. Pot and button bodies hang down from the lid above it.
+- **Under SEED**: R4 (lying flat) and pads P3/P4 sit right under SEED. Keep those two wires low and check how deep your SEED button reaches before closing the box.
+
+## Drill list
+
+Coordinates are from the lid's top-left corner, in mm, for the default sizes in the tool. Wall holes use x as drawn, which matches the lid view; heights are from the inside floor. Re-run the tool with your measured parts before drilling.
+
+| Where | Part | x mm | y mm | Hole |
+|---|---|---|---|---|
+| Lid | Screen wire hole (under the header) | 11 | 28 | Ø 8 |
+| Lid | Encoder | 15.5 | 61.5 | Ø 7 |
+| Lid | KICK | 83.5 | 20 | Ø 12 |
+| Lid | KICK 2 | 101.2 | 20 | Ø 12 |
+| Lid | SNARE | 118.8 | 20 | Ø 12 |
+| Lid | RUN toggle | 136.5 | 20 | Ø 6 |
+| Lid | HAT | 83.5 | 40 | Ø 12 |
+| Lid | HAT 16 | 101.2 | 40 | Ø 12 |
+| Lid | PERC | 118.8 | 40 | Ø 12 |
+| Lid | GHOST | 136.5 | 40 | Ø 12 |
+| Lid | BASS | 83.5 | 60 | Ø 12 |
+| Lid | MEL A | 101.2 | 60 | Ø 12 |
+| Lid | MEL B | 118.8 | 60 | Ø 12 |
+| Lid | PAD | 136.5 | 60 | Ø 12 |
+| Lid | ENERGY pot | 63 | 17.3 | Ø 7 |
+| Lid | DRIFT pot | 63 | 40 | Ø 7 |
+| Lid | SEED | 63 | 62.7 | Ø 16 |
+| Back wall | Jack MIDI IN | 105 | 20 down | Ø 6 |
+| Back wall | Jack OUT · KIT | 121 | 20 down | Ø 6 |
+| Back wall | Jack OUT · SYNTH | 137 | 20 down | Ø 6 |
+| Back wall | USB slot (Pico port) | 44 | 16 up from inside floor | 12 × 8 slot |