feat: Add Hardcover currently reading integration with i18n support

- Add CurrentlyReading component with beautiful design
- Integrate into About section
- Add German and English translations
- Add n8n API route for Hardcover integration
- Add comprehensive documentation for n8n setup

messages/de.json

@@ -60,6 +60,10 @@
         "gaming": "Gaming",
         "gameServers": "Game-Server einrichten",
         "jogging": "Joggen zum Kopf freibekommen und aktiv bleiben"
+      },
+      "currentlyReading": {
+        "title": "Aktuell am Lesen",
+        "progress": "Fortschritt"
       }
     },
     "projects": {