Fit sprite size to the texture aspect ratio

Add ↔ next to Width and ↕ next to Height in the inspector. Each sets its
field so the sprite matches the ratio of its assigned texture or frame,
reading the frame's own rect rather than the sheet's.

The buttons reuse the existing FieldActions convention, so they simply
do not appear when no texture is assigned, when the sprite is already
proportional, or on assets whose schema has no texture property.

Comparison is a cross product with a relative tolerance: 3135 of the
40000 size pairs up to 200x200 do not survive a round trip through a
division, so an exact check would leave the button standing after its
own click.

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

tools/e2e/index.mjs

@@ -17,6 +17,7 @@ import { menus } from './11-menus.mjs';
 import { textures } from './12-textures.mjs';
 import { frames } from './13-frames.mjs';
 import { overflow } from './14-overflow.mjs';
+import { aspect } from './15-aspect.mjs';
 
 export const STEPS = [
   hierarchy,
@@ -33,4 +34,5 @@ export const STEPS = [
   textures,
   frames,
   overflow,
+  aspect,
 ];