fix(website): spell plugin counts above ten in the hero

PLUGINS grew to 13, past the end of the number-word list, so the count fell
back to a number and toUpperCase failed during the static build.

website/src/components/Hero.astro

@@ -36,7 +36,13 @@ function wave(gain: (phase: number) => number): string {
 
 const dry = wave(() => 1);
 const knurled = wave(gainAt);
-const count = ['zero', 'one', 'two', 'three', 'four', 'five', 'six', 'seven', 'eight', 'nine', 'ten'][PLUGINS.length] ?? PLUGINS.length;
+const WORDS = [
+  'zero', 'one', 'two', 'three', 'four', 'five', 'six', 'seven', 'eight', 'nine', 'ten',
+  'eleven', 'twelve', 'thirteen', 'fourteen', 'fifteen', 'sixteen', 'seventeen', 'eighteen',
+  'nineteen', 'twenty',
+];
+// Spelled out up to twenty, digits after that.
+const count = WORDS[PLUGINS.length] ?? String(PLUGINS.length);
 ---
 
 <section class="hero">