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/editor/Editor.ts

@@ -9,6 +9,7 @@ import { pluginsOf } from '../core/store/projectPlugins';
 import type { FontStore } from '../core/store/FontStore';
 import type { SnapshotStore } from '../core/store/SnapshotStore';
 import type { SoundStore } from '../core/store/SoundStore';
+import { StreamKeeper } from './sound/StreamKeeper';
 import type { TextureStore } from '../core/store/TextureStore';
 import type { UsersStore } from '../core/store/UsersStore';
 import { gameClock, timeStep } from '../core/time';
@@ -249,6 +250,8 @@ export class Editor implements PlayHost {
   readonly shaderEditor: ShaderEditor;
   readonly particlesEditor: ParticlesEditor;
   readonly soundEditor: SoundEditor;
+  /** Makes the copies streamed sounds play from (#349). */
+  readonly streamKeeper: StreamKeeper;
   readonly soundFxEditor: SoundFxEditor;
   readonly instrumentEditor: InstrumentEditor;
   readonly patternEditor: PatternEditor;
@@ -349,7 +352,8 @@ export class Editor implements PlayHost {
     this.stateMachineEditor = new StateMachineEditor(state);
     this.shaderEditor = new ShaderEditor(state);
     this.particlesEditor = new ParticlesEditor(state);
-    this.soundEditor = new SoundEditor(state);
+    this.streamKeeper = new StreamKeeper(state, sounds);
+    this.soundEditor = new SoundEditor(state, this.streamKeeper);
     this.soundFxEditor = new SoundFxEditor(state);
     this.instrumentEditor = new InstrumentEditor(state);
     this.patternEditor = new PatternEditor(state, sounds);