feat: Implement blog and blog post models, routes, and services

- Added Blog and BlogPost models with necessary fields and relationships.
- Created blogRouter for handling blog-related API endpoints including CRUD operations.
- Developed BlogService for business logic related to blogs and posts, including sharing functionality.
- Implemented API client methods for frontend to interact with blog-related endpoints.
- Added internationalization support for blog-related text in English and German.
- Created Vue components for blog editing, listing, and viewing, including a rich text editor for post content.
- Enhanced user experience with form validations and dynamic visibility settings based on user input.

frontend/src/i18n/locales/de/blog.json

@@ -0,0 +1,11 @@
+{
+  "blog": {
+    "posts": "Beiträge",
+    "noPosts": "Keine Beiträge.",
+    "newPost": "Neuen Beitrag verfassen",
+    "title": "Titel",
+    "publish": "Veröffentlichen",
+    "pickImage": "Bild auswählen",
+    "uploadImage": "Bild hochladen"
+  }
+}

frontend/src/i18n/locales/de/navigation.json

@@ -16,6 +16,7 @@
         },
         "m-socialnetwork": {
             "guestbook": "Gästebuch",
+            "blog": "Blog",
             "usersearch": "Benutzersuche",
             "forum": "Forum",
             "gallery": "Galerie",