fix: eliminate forced reflows in TOC ScrollSpy + revert Bootstrap defer

- Replace scroll event listener with Intersection Observer in TableOfContentsRenderer
- Eliminates ~100ms forced reflows from offsetTop reads during scroll
- Revert Bootstrap CSS to blocking (media='all') - deferring caused CLS 0.954
- Keep CriticalBootstrapService available for future optimization
- Simplify CriticalCSSHooksRegistrar to only use CriticalCSSService

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Shared/Infrastructure/Wordpress/CriticalCSSHooksRegistrar.php

@@ -4,28 +4,22 @@ declare(strict_types=1);
 namespace ROITheme\Shared\Infrastructure\Wordpress;
 
 use ROITheme\Shared\Infrastructure\Services\CriticalCSSService;
-use ROITheme\Shared\Infrastructure\Services\CriticalBootstrapService;
 
 /**
- * Registra hooks wp_head para inyectar CSS crítico
+ * Registra hook wp_head para inyectar CSS crítico de componentes
  *
  * RESPONSABILIDAD:
- * - Registrar hook wp_head (priority 0) para Critical Bootstrap
  * - Registrar hook wp_head (priority 1) para Critical Component CSS
- * - Delegar renderizado a servicios especializados
+ * - Delegar renderizado a CriticalCSSService
  *
  * FLUJO:
- * 1. wp_head (priority 0) → CriticalBootstrapService::render()
- *    - Lee Assets/css/critical-bootstrap.css (subset ~8KB)
- *    - Output: <style id="roi-critical-bootstrap">...</style>
- *
- * 2. wp_head (priority 1) → CriticalCSSService::render()
+ * 1. wp_head (priority 1) → CriticalCSSService::render()
  *    - Consulta BD por componentes is_critical=true
  *    - Genera CSS usando Renderers
  *    - Output: <style id="roi-critical-css">...</style>
  *
- * 3. Bootstrap completo se carga diferido (media="print" + onload)
- *    - No bloquea renderizado inicial
+ * NOTA: CriticalBootstrapService está DESHABILITADO porque diferir
+ * Bootstrap causa CLS alto (0.954). Bootstrap carga bloqueante.
  *
  * PATRÓN:
  * - SRP: Solo registra hooks, delega lógica a servicios
@@ -37,8 +31,7 @@ use ROITheme\Shared\Infrastructure\Services\CriticalBootstrapService;
 final class CriticalCSSHooksRegistrar
 {
     public function __construct(
-        private readonly CriticalCSSService $criticalCSSService,
-        private readonly CriticalBootstrapService $criticalBootstrapService
+        private readonly CriticalCSSService $criticalCSSService
     ) {}
 
     /**
@@ -46,25 +39,10 @@ final class CriticalCSSHooksRegistrar
      */
     public function register(): void
     {
-        // Priority 0 = Critical Bootstrap (primero, antes de componentes)
-        add_action('wp_head', [$this, 'renderCriticalBootstrap'], 0);
-
-        // Priority 1 = Critical Component CSS (después de Bootstrap)
+        // Priority 1 = Critical Component CSS (hero, navbar, top-notification-bar)
         add_action('wp_head', [$this, 'renderCriticalCSS'], 1);
     }
 
-    /**
-     * Callback para wp_head - Critical Bootstrap
-     *
-     * Inyecta subset de Bootstrap (~8KB) inline:
-     * - Container, flexbox, navbar, dropdown
-     * - Output: <style id="roi-critical-bootstrap">...</style>
-     */
-    public function renderCriticalBootstrap(): void
-    {
-        $this->criticalBootstrapService->render();
-    }
-
     /**
      * Callback para wp_head - Critical Component CSS
      *