fix: correct circular --font-sans CSS variable; add nav links to login/register

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/app/page.tsx

@@ -1,4 +1,8 @@
+import Link from "next/link"
+
 import { AppShell } from "@/components/shell/app-shell"
+import { buttonVariants } from "@/components/ui/button"
+import { cn } from "cn"
 
 export default function Home() {
   return (
@@ -9,6 +13,17 @@ export default function Home() {
       <p className="mt-2 text-slate-600">
         Videoconferencia y grabación de reuniones para Appisoft SAS.
       </p>
+      <div className="mt-6 flex gap-3">
+        <Link href="/login" className={cn(buttonVariants())}>
+          Iniciar sesión
+        </Link>
+        <Link
+          href="/register"
+          className={cn(buttonVariants({ variant: "outline" }))}
+        >
+          Registrarse
+        </Link>
+      </div>
     </AppShell>
   )
 }