feat: restore sablog browse modes and clean imported HTML

Keep the public site readable after import (nbsp, highlighter, wrapping code, compact pager) and finish the admin extras already in this tree: sticky levels, preview, page cache, and live llms.txt.

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

plugins/demo.hello-world/src/ServiceProvider.php

@@ -6,6 +6,7 @@ namespace Plugins\Demo\HelloWorld;
 
 use App\Blog\Support\PluginManager;
 use App\Blog\Support\PluginServiceProvider;
+use App\Filament\Resources\Posts\Schemas\PostForm;
 use App\Models\Comment;
 use App\Models\Post;
 use App\Models\Setting;
@@ -53,8 +54,7 @@ class ServiceProvider extends PluginServiceProvider
 
         // 5. 后台表单注入示例：给文章编辑页加一个演示字段（meta.demo_note）
         $manager->addAction('filament.post_form', function (Schema $schema) {
-            $schema->components([
-                ...$schema->getComponents(),
+            PostForm::appendToSidebar($schema, [
                 Section::make('Hello World 演示')
                     ->collapsible()
                     ->schema([