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>

app/Providers/AppServiceProvider.php

@@ -41,6 +41,10 @@ class AppServiceProvider extends ServiceProvider
      */
     public function boot(): void
     {
+        config([
+            'filament-media-library.navigation_group' => '内容',
+        ]);
+
         // 自动加载所有插件的迁移（插件目录下 database/migrations）
         foreach (glob(base_path('plugins/*/database/migrations')) ?: [] as $path) {
             $this->loadMigrationsFrom($path);