feat: use xpier media library for uploads and markdown embeds

Store media:ID in post bodies instead of CDN URLs, and keep sablog attach tokens as a fallback.

Co-authored-by: Cursor <cursoragent@cursor.com>

plugins/neatstudio.blog-seo/src/Http/Middleware/SeoMiddleware.php

@@ -84,8 +84,8 @@ class SeoMiddleware
                     'mainEntityOfPage' => route('posts.show', $post->slug ?: $post->id),
                 ];
 
-                if ($cover = $post->getFirstMedia('cover')) {
-                    $data['image'] = [$cover->getUrl('card') ?: $cover->getUrl()];
+                if ($cover = $post->coverImageUrl()) {
+                    $data['image'] = [$cover];
                 }
 
                 return $data;