Image picker: tiles are containers, not graphics with children

The twin of the font picker fixed earlier today: every tile was a Graphics
carrying its sprite and caption, which Pixi v8 answers with "addChild:
Only Containers will be allowed to add children". The background moves
into its own Graphics inside a Container, and the step watches the console
while the picker opens, as the font one does.

Editor suite: 784 checks.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tools/e2e/12-textures.mjs

@@ -292,6 +292,7 @@ export async function textures(t) {
     JSON.stringify(afterUndo),
   );
 
+  await evaluate('__gm.console.clear()');
   await clickText('+');
   // By position, not by text: the menu entry "Texture" shares its label with the centre tab, and
   // `locate` would hand back whichever it walked into first.
@@ -324,6 +325,12 @@ export async function textures(t) {
     JSON.stringify({ spare: captionOf(spare), used: captionOf(texture.file), asset: texture.name }),
   );
   await shot('34-image-picker');
+  // A tile is a container holding its background, not a Graphics with children: Pixi v8 warns
+  // about the latter, and the warning is the only sign that the tiles are built the wrong way.
+  const tileComplaints = (await json('__gm.console.lines()')).filter((line) =>
+    /Deprecation/i.test(JSON.stringify(line)),
+  );
+  check('building the tiles draws no complaint from Pixi', tileComplaints.length === 0, tileComplaints);
 
   const tile = await json(`__gm.imagePickerTile(${JSON.stringify(spare)})`);
   await click(tile.x, tile.y);