Cut a sound to a stretch of its file in its own Sound tab (#343)

A sound asset now opens in a tab that shows its file as a waveform.
Two handles set where the sound starts and ends in the file, and that
stretch is the sample: Play sound, a song item and an instrument's
Sample all play it and nothing else. The file itself is never changed.

- The asset has three new rows: Start (s), End (s) and Edge fade (ms).
  End 0 is the end of the file, the fade is 10 ms by default. Older
  assets have no values and play the whole file as before.
- Every way of playing asks playedSoundOf() for a name instead of the
  file: the file, or <file>#<start>~<end>~<fade> for a cut.
- SoundLibrary makes the cut from the decoded file the first time that
  name plays and ramps each edge inside the file over the fade. Length
  and peaks of a cut are read from the file without a copy.
- Cut buffers can be made again at any time, so the library lets the
  oldest go past 64 Mi samples. A voice holds its buffers itself.
- The tab draws min/max per pixel from 256-sample block peaks, and the
  samples as a line when zoomed in far. Wheel zooms, the middle button
  pans, as in the music tabs. Wave, cut and ruler sit under a mask,
  so a handle panned out of view does not draw over the panels beside.
- Dragging a handle moves that edge, dragging elsewhere spans a new
  stretch. One drag is one undo step for both edges. Whole file puts
  the handles back, Play or Space plays the stretch with a playhead.
- The inspector preview and the Sound FX preview play the cut too, and
  the song lanes draw and repeat it.

Tests:
- Unit: sounds 20, wave-view 8 (new), sound-library 68, plus 258 in
  the touched areas (instrument, song, pattern, inspector, tabs)
- e2e 34 on melektaus-atx: ALL PASSED, 57 checks (7 new)
- Gate on melektaus-atx: CHECK EXIT 0, 253 files, 3936 tests

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

src/editor/debugHook.ts

@@ -13,6 +13,7 @@ import {
   stageNodes,
 } from '../viewport/SoundLibrary';
 import { curveHooks } from './debug/curveHooks';
+import { soundHooks } from './debug/soundHooks';
 import { patternHooks } from './debug/patternHooks';
 import { songHooks } from './debug/songHooks';
 import { documentHooks } from './debug/documentHooks';
@@ -48,6 +49,7 @@ export function installDebugHook(app: Application, state: EditorState, editor: E
     ...curveHooks(context),
     ...patternHooks(context),
     ...songHooks(context),
+    ...soundHooks(context),
     ...renderHooks(context),
     /**
      * Voices started, stopped and in flight. CI runs the browser with `--mute-audio`, so nothing