feat: improve SEO with locale-specific metadata, structured data, and keywords

- Add locale-specific title/description for DE and EN homepage
- Expand keywords with local SEO terms (Webentwicklung Osnabrück, Informatik, etc.)
- Add WebSite schema and enhance Person schema with knowsAbout, alternateName
- Add hreflang alternates for DE/EN
- Update projects page with locale-specific metadata
- Keep visible titles short, move SEO terms to description/structured data

app/layout.tsx

@@ -49,23 +49,33 @@ export default async function RootLayout({
 export const metadata: Metadata = {
   metadataBase: new URL(getBaseUrl()),
   title: {
-    default: "Dennis Konkol | Portfolio",
-    template: "%s | Dennis Konkol",
+    default: "Dennis Konkol",
+    template: "%s | dk0",
   },
   description:
-    "Portfolio of Dennis Konkol, a student and software engineer based in Osnabrück, Germany. Passionate about technology, coding, and solving real-world problems.",
+    "Dennis Konkol – Software Engineer & Webentwickler in Osnabrück. Webentwicklung, Fullstack-Apps, Docker, Next.js, Flutter. Portfolio mit Projekten und Kontakt.",
   keywords: [
     "Dennis Konkol",
+    "dk0",
+    "denshooter",
+    "Webentwicklung Osnabrück",
+    "Webentwicklung",
+    "Softwareentwicklung Osnabrück",
+    "Website erstellen Osnabrück",
+    "Web Design Osnabrück",
+    "Informatik Osnabrück",
     "Software Engineer",
-    "Portfolio",
-    "Student",
-    "Web Development",
     "Full Stack Developer",
-    "Osnabrück",
-    "Germany",
-    "React",
+    "Frontend Developer Osnabrück",
     "Next.js",
+    "React",
     "TypeScript",
+    "Flutter",
+    "Docker",
+    "Self-Hosting",
+    "DevOps",
+    "Portfolio",
+    "Osnabrück",
   ],
   authors: [{ name: "Dennis Konkol", url: "https://dk0.dev" }],
   creator: "Dennis Konkol",
@@ -82,26 +92,27 @@ export const metadata: Metadata = {
     },
   },
   openGraph: {
-    title: "Dennis Konkol | Portfolio",
+    title: "Dennis Konkol",
     description:
-      "Explore my projects and contact me for collaboration opportunities!",
+      "Software Engineer & Webentwickler in Osnabrück. Next.js, Flutter, Docker, DevOps. Projekte ansehen und Kontakt aufnehmen.",
     url: "https://dk0.dev",
-    siteName: "Dennis Konkol Portfolio",
+    siteName: "Dennis Konkol",
     images: [
       {
         url: "https://dk0.dev/api/og",
         width: 1200,
         height: 630,
-        alt: "Dennis Konkol Portfolio",
+        alt: "Dennis Konkol",
       },
     ],
-    locale: "en_US",
+    locale: "de_DE",
+    alternateLocale: ["en_US"],
     type: "website",
   },
   twitter: {
     card: "summary_large_image",
-    title: "Dennis Konkol | Portfolio",
-    description: "Student & Software Engineer based in Osnabrück, Germany.",
+    title: "Dennis Konkol",
+    description: "Software Engineer & Webentwickler in Osnabrück.",
     images: ["https://dk0.dev/api/og"],
     creator: "@denshooter",
   },
@@ -110,5 +121,9 @@ export const metadata: Metadata = {
   },
   alternates: {
     canonical: "https://dk0.dev",
+    languages: {
+      de: "https://dk0.dev/de",
+      en: "https://dk0.dev/en",
+    },
   },
 };