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.

backend/routers/blogRouter.js

@@ -0,0 +1,32 @@
+import { Router } from 'express';
+import { authenticate } from '../middleware/authMiddleware.js';
+import multer from 'multer';
+import { createBlog, updateBlog, listBlogs, getBlog, createPost, listPosts, listBlogImages, uploadBlogImage, getPublicBlogImageByHash, shareBlog, resolveBlogSlug, resolveBlogSlugId } from '../controllers/blogController.js';
+
+const upload = multer();
+
+const router = Router();
+
+// Public list (filtered by visibility); if logged in, pass userid in headers for access
+router.get('/blogs', listBlogs);
+// Public get (access enforced per blog)
+router.get('/blogs/:id', getBlog);
+// Public list posts (access enforced per blog)
+router.get('/blogs/:id/posts', listPosts); // supports ?page=&pageSize=
+// Public serve image by hash if folder has 'everyone' visibility
+router.get('/blogs/images/:hash', getPublicBlogImageByHash);
+// Public: resolve pretty slug to SPA route and JSON id
+router.get('/blogs/slug/:slug', resolveBlogSlug);
+router.get('/blogs/slug/:slug/id', resolveBlogSlugId);
+
+// Create/Update require login (any logged-in user can create/edit their own blog); posts require login
+router.post('/blogs', authenticate, createBlog);
+router.put('/blogs/:id', authenticate, updateBlog);
+router.post('/blogs/:id/posts', authenticate, createPost);
+router.post('/blogs/:id/share', authenticate, shareBlog);
+
+// Blog images: list and upload to user's Blog folder
+router.get('/blogs/:id/images', authenticate, listBlogImages);
+router.post('/blogs/:id/images', authenticate, upload.single('image'), uploadBlogImage);
+
+export default router;