fix(demos): forma — add `full` to the magnitude control (radius scale already had it)

The radius scale ships `--radius-full` (9999px = pill / totally-rounded); the
/temas/forma magnitude chips just omitted it (sm/md/lg/xl). Added `full` so the demo
exposes totally-rounded. Magnitude (rounded / --radius-*) is orthogonal to the shape
family (corner-shape).

Verified: check 0 errors; card --sample-radius -> 9999px on `full`.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/routes/temas/forma/+page.svelte

@@ -40,7 +40,7 @@
 	let nest = $state(true)
 	let playing = $state(true)
 
-	const RADII = ['sm', 'md', 'lg', 'xl'] as const
+	const RADII = ['sm', 'md', 'lg', 'xl', 'full'] as const
 
 	// ── 4 · eventful press ───────────────────────────────────────────────────────
 	let pressed = $state<string | null>(null)