Keep a pixel frame worn through a shader alive while it is drawn

Changing a palette colour of pixel art flooded the console with Pixi
warnings: "[BindGroup] a 'textureSource' was destroyed while still
bound to a shader", and the same for its sampler. #293 had stopped
this for a drawing, but a frame of pixel art is worn as a cut of the
sheet. The cut has a source of its own, so the sheet looked unbound,
was freed at once and took the cut with it under the shader.

- The check whether a replaced picture is still in use gets its key
  too. TextureLibrary then asks the picture and every cut taken from
  it.
- A sheet with a bound cut waits like a bound picture did since #293,
  and both go together once the shader has taken the new frame.

Found on the way:

- The project the report came from has a sprite wearing a frame of
  an eleven-frame pixel art through a shader asset.
- A nine-sliced sprite wearing the frame showed no warning, even
  without the change. The first try of the e2e check used it.

Tests:
- Gate on melektaus-atx: 236 files, 3577 tests (+1)
- e2e 48: 45 checks (+1, sum 1741). 48l-iii puts a shader on the
  object wearing the second frame, changes a palette colour three
  times and counts the warnings.
- Counter-checks bite: without the cuts in the check the unit test
  fails, and 48l-iii counts 6 warnings for 3 changes.

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

tools/e2e/48-pixelart.mjs

@@ -705,6 +705,37 @@ export async function pixelArt(t) {
     delete art.props.sliceScale;`);
   await settle();
 
+  // 48l-iii. The object wears the frame through a shader asset: its mesh names a cut of the sheet,
+  //          which has a source of its own. A palette colour changed under it freed the sheet at
+  //          once and the cut with it, and Pixi warned for the source and its sampler every time.
+  await mutate(`
+    Object.assign(__gm.state.activeScene.objects.find((o) => o.id === 'pa-object').overrides,
+      { shader: 'adjust-colors', saturation: 0 })`);
+  await settle();
+  await sleep(300);
+  const boundLogFrom = t.consoleLog.length;
+  const waiting = [];
+  for (const color of [0x3050a0, 0x70b030, 0xff004d]) {
+    await mutate(`
+      const p = __gm.state.project;
+      const art = p.assets.find((a) => a.id === ${JSON.stringify(id)});
+      p.assets.find((a) => a.id === art.props.palette).colors[${RED - 1}] = ${color};`);
+    await settle();
+    await sleep(200);
+    waiting.push((await json('__gm.picturesWaiting()')).length);
+  }
+  const boundWarnings = t.consoleLog.slice(boundLogFrom).filter((line) => line.includes('BindGroup'));
+  check(
+    'a palette colour changed under a frame worn through a shader warns of no destroyed texture',
+    boundWarnings.length === 0 && waiting.every((n) => n === 0),
+    JSON.stringify({ warnings: boundWarnings.length, waiting }),
+  );
+  await mutate(`
+    const o = __gm.state.activeScene.objects.find((o) => o.id === 'pa-object');
+    delete o.overrides.shader;
+    delete o.overrides.saturation;`);
+  await settle();
+
   const textureRow = await json("__gm.inspectorField('Texture', true)");
   await click(textureRow.x, textureRow.y);
   await settle();