Rename /ueber-bjoern to /ueber-mich, link it in the nav

Nav's "Über Björn" entry pointed to the homepage's #ueber-bjoern
teaser section, not the new bio page — updated the label to "Über
mich" and the href to the real /ueber-mich page. The homepage's own
#ueber-bjoern anchor id (About.tsx) is untouched, it's a separate
section.

app/components/Navbar.tsx

@@ -46,7 +46,7 @@ function getNavLinks(singleActiveProduct: boolean) {
   return [
     { label: "Werkzeuge", href: "#werkzeuge" },
     { label: "Blog", href: "/blog" },
-    { label: "Über Björn", href: "#ueber-bjoern" },
+    { label: "Über mich", href: "/ueber-mich" },
     { label: "Shop", href: singleActiveProduct ? "#spotlight" : "/shop" },
   ];
 }

app/ueber-mich/page.tsx

@@ -11,11 +11,11 @@ const description =
 export const metadata: Metadata = {
   title,
   description,
-  alternates: { canonical: "/ueber-bjoern" },
+  alternates: { canonical: "/ueber-mich" },
   openGraph: {
     title,
     description,
-    url: "/ueber-bjoern",
+    url: "/ueber-mich",
     type: "profile",
     images: ["/about-author.jpg"],
   },
@@ -65,7 +65,7 @@ const highlights = [
   "Ehrliche Einblicke statt Perfektionsfassade",
 ];
 
-export default function UeberBjoernPage() {
+export default function UeberMichPage() {
   return (
     <>
       <main className="flex flex-col flex-1 bg-bg-base">