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/index.html

@@ -28,13 +28,26 @@
     <meta name="twitter:card" content="summary" />
 
     <!-- IBM Plex Mono is the brand typeface. CDN rather than self-hosted
-         binaries, matching the design system's tokens/fonts.css. OFL 1.1. -->
+         binaries, matching the design system's tokens/fonts.css. OFL 1.1.
+
+         Loaded non-blocking: as a plain stylesheet it sat on the critical
+         path, so first paint waited on a third-party DNS + TLS + fetch. It
+         buys nothing there — `display=swap` plus the ui-monospace fallback
+         means the first frame renders in the fallback either way. -->
     <link rel="preconnect" href="https://fonts.googleapis.com" />
     <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin />
     <link
-      rel="stylesheet"
+      rel="preload"
+      as="style"
       href="https://fonts.googleapis.com/css2?family=IBM+Plex+Mono:wght@400;500;700&display=swap"
+      onload="this.onload=null;this.rel='stylesheet'"
     />
+    <noscript>
+      <link
+        rel="stylesheet"
+        href="https://fonts.googleapis.com/css2?family=IBM+Plex+Mono:wght@400;500;700&display=swap"
+      />
+    </noscript>
 
     <script>
       // Runs before first paint so the right theme is already on <html>.