Zoom the height of a sound's wave over its level scale (#357)

The Sound tab always drew the wave at the full height of the tab. Quiet
stretches were hard to see, and there was no room above a loud wave.

- A level scale in dB stands left of the wave, a mark every 6 dB down
  from 0, as long as a mark lies inside the area and at least 14 px
  from the middle.
- The wheel over the scale zooms the height, from 0.25x to 16x. Over
  the wave it zooms the time as before.
- What is louder than the area stops at its edge. The fade ramps grow
  with the wave.
- Fit puts the height back to 1x. The tab keeps the height with its
  view when another tab is shown.
- The rules live in waveView.ts (zoomLevel, levelMarks), the hooks
  give the height, the scale and the top of a full-scale wave.

Tests:
- Unit wave-view: 10 green (2 new), 2 counter-checks each red
- e2e 34 (melektaus-atx): ALL PASSED, 87 checks (1 new)
- Gate (melektaus-atx): CHECK EXIT 0, 270 files, 4183 tests

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

tools/e2e/34-sound.mjs

@@ -1933,6 +1933,42 @@ export async function sound(t) {
       tabOpened.info === '0.75 s',
     JSON.stringify(tabOpened),
   );
+  // 34h-2a. The wheel over the level scale left of the wave zooms its height (#357): out leaves room
+  //         above a full-scale wave, in takes it past the top of the tab, the seconds stay where they
+  //         are, and Fit brings back the full height.
+  const levelScale = await json('__gm.soundTab.scale()');
+  const levelRect = await json('__gm.soundTab.rect()');
+  const fullTop = await json('__gm.soundTab.fullScaleTop()');
+  const secondAt = (await json('__gm.soundTab.at(0.5)')).x;
+  await t.wheel(levelScale.x, levelScale.y, 924);
+  const zoomedOut = {
+    level: await json('__gm.soundTab.level()'),
+    top: await json('__gm.soundTab.fullScaleTop()'),
+    secondAt: (await json('__gm.soundTab.at(0.5)')).x,
+  };
+  await t.wheel(levelScale.x, levelScale.y, -1848);
+  const zoomedIn = {
+    level: await json('__gm.soundTab.level()'),
+    top: await json('__gm.soundTab.fullScaleTop()'),
+  };
+  const levelFit = await json('__gm.soundTab.fitButton()');
+  await click(levelFit.x, levelFit.y);
+  await sleep(100);
+  const refitted = {
+    level: await json('__gm.soundTab.level()'),
+    top: await json('__gm.soundTab.fullScaleTop()'),
+  };
+  check(
+    'the wheel over the level scale zooms the height alone, and Fit puts it back',
+    Math.abs(zoomedOut.level - 0.25) < 0.01 &&
+      Math.abs(zoomedOut.top - levelScale.y - (fullTop - levelScale.y) * 0.25) < 1 &&
+      zoomedOut.secondAt === secondAt &&
+      Math.abs(zoomedIn.level - 4) < 0.05 &&
+      zoomedIn.top < levelRect.y &&
+      refitted.level === 1 &&
+      Math.abs(refitted.top - fullTop) < 0.5,
+    JSON.stringify({ levelScale, levelRect, fullTop, secondAt, zoomedOut, zoomedIn, refitted }),
+  );
   const droneProps = async () => (await assetsOfType('sound')).find((a) => a.id === droneId)?.props;
   let dragFrom = await json('__gm.soundTab.at(0.75)');
   let dragTo = await json('__gm.soundTab.at(0.5)');