Stream long sounds from an Opus copy instead of decoding them (#349)

A sound was decoded whole as soon as the project opened, in the editor
and in a released game: five minutes of stereo held some 115 MB for as
long as the page was open. A sound with Stream on now plays from a copy
as Opus in Ogg, fetched a piece at a time and decoded a few seconds
ahead by WebCodecs, so a game holds a few megabytes for it.

- The Stream switch is a row of the sound, off by default. The Sound
  tab suggests it from a minute on and says how far the copy has got.
- StreamKeeper makes the copies in the browser, a moment after the
  last change, one at a time: the sound's own and one per clip of its
  cut, fades and Reverse baked in. A copy that is no longer wanted is
  taken off and deleted once the project is saved without it.
- streamTable says which played names stream from which copy. A clip
  without a fitting copy, a Sample and a Reverb impulse stay decoded.
  A sound with Stream on is never decoded ahead.
- The page fetches by Range and takes the whole file from a server
  that ignores it, as the CI's PHP server does. It keeps the bytes
  and the first two seconds decoded, the rest goes four seconds ahead.
- A jump decodes 32 packets before the place first. Measured in
  Chrome, what follows is then the same to the bit as decoding from
  the start. With 4 packets it was 0.06 off.
- The stream-player on the FX worklet reads the samples at the rate
  of the context along a Catmull-Rom curve. What comes late is silent
  and skipped once it is there, so a clip keeps its beat.
- The opening stretch goes with the player as it is made. Sent by
  message it came a few milliseconds late, and 557 samples of the
  attack were lost.
- Pitch on a streamed sound is a shifter after the player, as on a
  bus: the length stays and it is heard 42.7 ms late.
- Bakes of patterns and songs (#340) always stream now.
- The song timeline draws a streamed sound from its copy decoded at
  8 kHz, keeping only the peaks.

Tests:
- Gate: CHECK EXIT 0, 280 files, 4312 tests (31 new: ogg +3,
  stream-queue 6, streams 11, streaming 6, sound-library +5).
- e2e 34: ALL PASSED, 106 checks (7 new). Five minutes of mono,
  4.8 MB as WAV, 3.6 MB as its copy: streamed the renderer grows by
  5.8 MB, decoded by 69.6 MB. Offline at 48 kHz, start, loop seam and
  a reversed clip are the copy decoded whole to the sample (0).
- Counter-checks red as they should be: no pre-roll, no catch-up of
  late samples at the end, no opening stretch, a streamed sound
  decoded ahead.

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

src/core/store/serialize.ts

@@ -22,6 +22,7 @@ import { isShaderNodeDef } from '../shader/nodes';
 import { isSoundFxNodeDef } from '../soundfx/nodes';
 import { INSTRUMENT_SAMPLE, isInstrumentNodeDef, withSamplePlay } from '../instrument/nodes';
 import { heldBake } from '../music/bake';
+import { heldStream } from '../music/streams';
 import { heldPatternNotes } from '../music/pattern';
 import { isEmbeddable } from '../music/embedded';
 import { heldSongItems, heldSongTracks } from '../music/song';
@@ -263,7 +264,16 @@ export function deserializeProject(raw: unknown, fallbackId = ''): Project {
     } else if (type === 'sound') {
       const file = typeof a.file === 'string' && isSoundFile(a.file) ? a.file : '';
       const clips = normalizeClips(a.clips, takenIds);
-      assets.push({ id, type, name, props, file, ...(clips.length > 0 && { clips }) });
+      const stream = heldStream(a.stream);
+      assets.push({
+        id,
+        type,
+        name,
+        props,
+        file,
+        ...(clips.length > 0 && { clips }),
+        ...(stream && { stream }),
+      });
     } else if (type === 'tile') {
       // A picture naming nothing is kept, like an animation's dangling root: it reads as missing
       // in the tab and comes back when the texture it named is restored by an undo.
@@ -763,10 +773,12 @@ function normalizeClips(raw: unknown, takenIds: Set<string>): SoundClip[] {
     const id = typeof c.id === 'string' ? c.id : '';
     if (!id || takenIds.has(id)) continue;
     takenIds.add(id);
+    const stream = heldStream(c.stream);
     clips.push({
       id,
       name: typeof c.name === 'string' ? c.name : '',
       props: normalizeBag(c.props, CLIP_ROWS, true),
+      ...(stream && { stream }),
     });
   }
   return clips;