fix(website): clear WCAG AA across both themes, and stop the hero shifting

Contrast was measured, not eyeballed: 41 foreground/background pairs across
both themes and the terminal surface, each against the darkest (light) or
lightest (dark) surface it actually sits on. Five failed. Links on manila
read 3.64:1 and the footer's "No telemetry. Ever." — a claim the site goes
out of its way to make — sat at 2.86:1.

The accent needed splitting rather than moving. #c1502e clears 4.5:1 as a
button fill behind white but only 3.99:1 as an 11px eyebrow on vinyl, so
--accent keeps the brand hue for fills and a new --accent-text carries the
readable cut. The terminal gets the same treatment dark emulators give their
palettes: alarm and oxide brighten inside .tui-content so "Failed" is
legible next to its glyph.

Reduced motion no longer nukes everything. A blanket 0.01ms also kills the
transitions that answer a click, which is feedback rather than movement;
looping and travelling animation stops, the rest caps at 80ms. The TUI
already skipped its opening run and still does.

The hero reserves its box with aspect-ratio from the first paint. It was
prerendered at full unscaled height and collapsed once JS measured, moving
everything below it by ~145px. Measured shift is now 0.

Also: the webfont loads non-blocking (display=swap meant the first frame
never waited for it anyway), footer link groups nest under a heading instead
of sitting level with page sections, and eight tokens nothing referenced
stop shipping.

website/src/pages/install.tsx

@@ -76,7 +76,7 @@ interface StepProps {
 
 const Step = ({ n, title, children }: StepProps) => (
   <div className="grid grid-cols-1 gap-3 sm:grid-cols-[auto_1fr] sm:gap-5">
-    <div className="flex size-[34px] items-center justify-center rounded-md border border-line text-sm text-accent">
+    <div className="flex size-[34px] items-center justify-center rounded-md border border-line text-sm text-accent-text">
       {n}
     </div>
     <div className="flex min-w-0 flex-col gap-3">