Make an 8-bit sound with a Preset, Randomize or Mutate (#329)

A Chip could play a sound, but finding a good one meant typing a dozen
numbers. sfxr's buttons do that in one click: a kind of sound drawn
anew every time, a wild draw, or a small nudge. The Instrument tab now
has the same, and plays the result at once.

- Preset menu with Pickup, Laser, Explosion, Powerup, Hit, Jump and
  Blip. It puts a new graph in place of the instrument's, as one undo
  step: Notes for all 128 notes, Chip, Envelope, Filter, Bitcrusher,
  Output. The Chip keeps its own frequency with follow note off, so
  every key plays the same effect, and sustain 0 ends it by itself.
- The presets are sfxr's generators, worked out into Hz, semitones and
  seconds with sfxr's own formulas, in chipPresets.ts. sfxr's envelope
  holds and falls in a line, ours falls quick at first. So the decay
  is three times sfxr's hold and fall.
- Randomize draws every number of the Chips, Envelopes, Filters and
  Bitcrushers anew, as sfxr's randomizer does. Waves, filter types,
  the Bitcrusher's mix and an Envelope's from and to stay.
- Mutate moves each of those numbers a little, one in two. A 0 stays
  0, so nothing that was off comes on.
- An input fed by an edge is left alone by both. Both are grey while
  the graph has none of those nodes.
- Audition, off by default as in the Pattern tab, plays the note last
  played again 150 ms after a change to the graph rests.
- Preset, Randomize and Mutate always play that note, for up to 2 s.
- ReplaceGraphCommand swaps nodes and edges and keeps groups and notes.
- The info on the right of the header kept 220 px and was cut off
  with the four new buttons. 140 px still fit "No sound picked".

Not done: punch, filter sweeps and the phaser of sfxr (#341).

Tests:
- Unit chip-presets (new) 7. Counter-check: a wrong Hz formula and
  fed inputs not left alone turn 3 of them red. Unit tests of the
  instrument tab, graph commands and sound FX nodes: 49 files, 851
  green.
- e2e 34 (melektaus-atx): ALL PASSED, 64 checks (4 new): Preset,
  Randomize and Mutate, Audition, three undos back to the Sample.
- Screenshot with a Laser preset: the header fits at 1280 px, the
  chain is fitted, the Chip is a saw with its duty grey.
- Gate (melektaus-atx): CHECK EXIT 0, 256 files, 3969 tests.

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

src/editor/debug/graphHooks.ts

@@ -135,6 +135,13 @@ export function graphHooks({ state, editor }: HookContext) {
       }),
       keyAt: (note: number) => editor.instrumentEditor.keyboard.keyCentre(note),
       stopAt: () => centreOf(editor.instrumentEditor.stopButton),
+      presetAt: () => centreOf(editor.instrumentEditor.presetButton),
+      randomizeAt: () => centreOf(editor.instrumentEditor.randomizeButton),
+      mutateAt: () => centreOf(editor.instrumentEditor.mutateButton),
+      auditionAt: () => ({
+        ...centreOf(editor.instrumentEditor.auditionButton),
+        toggled: editor.instrumentEditor.auditionButton.toggled,
+      }),
       params: () => editor.instrumentEditor.previewValues,
       setParam: (key: string, value: number) => editor.instrumentEditor.setPreviewValue(key, value),
     },