The animation tab's Fit frames the preview, and the separate Centre button is gone (#111)

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

tools/e2e/25-animation.mjs

@@ -135,8 +135,8 @@ export async function animation(t) {
     return json(`__gm.animation.preview.rect(${JSON.stringify(armId)})`);
   };
   await scrubTo(10);
-  const centre = await json('__gm.animation.preview.centreAt()');
-  await click(centre.x, centre.y);
+  const fit = await json('__gm.animation.preview.fitAt()');
+  await click(fit.x, fit.y);
   await sleep(200);
   const start = await rectAt(0);
   const end = await rectAt(10);