Strip www. prefix from social link display values on contact page

The regex now removes both https:// and an optional www. prefix,
so https://www.linkedin.com displays as linkedin.com instead of
www.linkedin.com — consistent with github.com and x.com.

https://claude.ai/code/session_019mp7rTrQPx9yxp17hgjsYb

src/pages/contact.astro

@@ -26,7 +26,7 @@ const channels = [
   ...socialLinks.map((link) => ({
     icon: link.icon,
     label: link.label,
-    value: link.href.replace(/^https?:\/\//, ''),
+    value: link.href.replace(/^https?:\/\/(www\.)?/, ''),
     note: 'Follow along',
     href: link.href,
     external: true,