feat(seo): enhance multilingual support and SEO handling

- Added support for multiple languages in the frontend, including English, Spanish, and Cebuano, improving accessibility for a broader audience.
- Implemented hreflang links for better SEO performance, ensuring search engines can correctly index language-specific content.
- Updated SEO metadata handling to utilize internationalization keys, enhancing the clarity and relevance of page titles and descriptions.
- Refactored SEO utility functions to streamline the management of OpenGraph and hreflang attributes, improving maintainability and performance.

frontend/src/views/blog/BlogView.vue

@@ -46,7 +46,16 @@
 import { getBlog, listPosts, createPost } from '@/api/blogApi.js';
 import DOMPurify from 'dompurify';
 import RichTextEditor from './components/RichTextEditor.vue';
-import { applySeo, buildAbsoluteUrl, createBlogSlug, stripHtml, truncateText } from '@/utils/seo.js';
+import {
+  applySeo,
+  buildAbsoluteUrl,
+  createBlogSlug,
+  stripHtml,
+  truncateText,
+  seoSchemaLang,
+  seoOgLocale,
+  seoHtmlLang,
+} from '@/utils/seo.js';
 export default {
   name: 'BlogView',
   props: { id: String, slug: String },
@@ -92,13 +101,20 @@ export default {
       const summarySource = this.blog.description || plainTextPosts || this.$t('blog.view.fallbackDescription');
       const description = truncateText(summarySource, 160);
       const canonicalPath = this.canonicalBlogPath();
+      const uiLang = this.$store.state.language;
+      const pageTitle = this.$te('seo.blogPost.pageTitle')
+        ? this.$t('seo.blogPost.pageTitle', { title: this.blog.title })
+        : `${this.blog.title} | YourPart`;
 
       applySeo({
-        title: `${this.blog.title} | Blog auf YourPart`,
+        title: pageTitle,
         description,
         canonicalPath,
         keywords: `Blog, ${this.blog.title}, ${this.blog.owner?.username || 'YourPart'}, Community`,
         type: 'article',
+        locale: seoOgLocale(uiLang),
+        lang: seoHtmlLang(uiLang),
+        includeHreflangAlternates: true,
         jsonLd: [
           {
             '@context': 'https://schema.org',
@@ -106,7 +122,7 @@ export default {
             name: this.blog.title,
             description,
             url: buildAbsoluteUrl(canonicalPath),
-            inLanguage: 'de',
+            inLanguage: seoSchemaLang(uiLang),
             author: this.blog.owner?.username
               ? {
                   '@type': 'Person',
@@ -150,6 +166,9 @@ export default {
         description: this.$t('blog.view.notFoundDescription'),
         canonicalPath: '/blogs',
         robots: 'noindex, nofollow',
+        locale: seoOgLocale(this.$store.state.language),
+        lang: seoHtmlLang(this.$store.state.language),
+        includeHreflangAlternates: true,
       });
     } finally { this.loading = false; }
     },