feat(i18n): add English contact page implementation with localization support

Author: mikerb95

src/pages/en/contact.astro

@@ -0,0 +1,8 @@
+---
+// Cascarón de ruta: la implementación real vive en src/pages/contact.astro.
+// Ver docs/plan-i18n-en.md §2.3.
+import Contact from '../contact.astro'
+export const prerender = false
+---
+
+<Contact />