feat: add client component demonstrating Pretext text measurement

src/components/MeasuredText.tsx

@@ -0,0 +1,39 @@
+'use client';
+
+import { useEffect, useRef, useState } from 'react';
+import { measureText } from '@chenglou/pretext';
+
+interface MeasuredTextProps {
+  text: string;
+}
+
+export default function MeasuredText({ text }: MeasuredTextProps) {
+  const ref = useRef<HTMLSpanElement>(null);
+  const [width, setWidth] = useState<number | null>(null);
+
+  useEffect(() => {
+    if (!ref.current) return;
+
+    const style = window.getComputedStyle(ref.current);
+    const measured = measureText(text, {
+      font: {
+        family: style.fontFamily.split(',')[0].replace(/['"]/g, ''),
+        size: parseFloat(style.fontSize),
+        weight: style.fontWeight,
+      },
+    });
+
+    setWidth(measured.width);
+  }, [text]);
+
+  return (
+    <div>
+      <span ref={ref} style={{ fontSize: '2rem', fontWeight: 700 }}>
+        {text}
+      </span>
+      {width !== null && (
+        <p style={{ color: 'dimgray' }}>Measured width: {width.toFixed(2)}px</p>
+      )}
+    </div>
+  );
+}