feat(pagespeed): implement YouTube Facade Pattern - Phase 2.4

PageSpeed Optimization to reduce TBT by ~2000ms:
- Add YoutubeFacade module following Clean Architecture
- Replace YouTube iframes with thumbnail + play button
- Load real iframe only on user click (lazy-load)
- Reduces initial page blocking time significantly

Files added:
- Public/YoutubeFacade/Infrastructure/Wordpress/YoutubeFacadeHooksRegistrar.php
- Public/YoutubeFacade/Infrastructure/Services/YoutubeFacadeContentFilter.php
- Public/YoutubeFacade/Infrastructure/Ui/YoutubeFacadeRenderer.php
- Public/YoutubeFacade/Infrastructure/Ui/Assets/Css/youtube-facade.css
- Public/YoutubeFacade/Infrastructure/Ui/Assets/Js/youtube-facade.js

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

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

Public/YoutubeFacade/Infrastructure/Services/YoutubeFacadeContentFilter.php

@@ -0,0 +1,54 @@
+<?php
+
+declare(strict_types=1);
+
+namespace ROITheme\Public\YoutubeFacade\Infrastructure\Services;
+
+use ROITheme\Public\YoutubeFacade\Infrastructure\Ui\YoutubeFacadeRenderer;
+
+/**
+ * Filters post content to replace YouTube iframes with facades
+ *
+ * Detects YouTube iframes (including those wrapped in .video-wrapper)
+ * and replaces them with lightweight facade HTML.
+ *
+ * @package ROITheme\Public\YoutubeFacade
+ * @since 1.0.6
+ */
+final class YoutubeFacadeContentFilter
+{
+    private YoutubeFacadeRenderer $renderer;
+
+    public function __construct(YoutubeFacadeRenderer $renderer)
+    {
+        $this->renderer = $renderer;
+    }
+
+    /**
+     * Filter content to replace YouTube iframes with facades
+     *
+     * @param string $content Post content
+     * @return string Filtered content
+     */
+    public function filter(string $content): string
+    {
+        // Match YouTube iframes (with or without video-wrapper)
+        // Pattern handles both youtube.com/embed/ and youtube-nocookie.com/embed/
+        $pattern = '/<div class="video-wrapper">\s*<iframe[^>]*src="https?:\/\/(?:www\.)?(?:youtube\.com|youtube-nocookie\.com)\/embed\/([a-zA-Z0-9_-]+)[^"]*"[^>]*><\/iframe>\s*<\/div>/is';
+
+        $content = preg_replace_callback($pattern, function ($matches) {
+            $videoId = $matches[1];
+            return $this->renderer->render($videoId);
+        }, $content);
+
+        // Also match standalone iframes without wrapper
+        $patternStandalone = '/<iframe[^>]*src="https?:\/\/(?:www\.)?(?:youtube\.com|youtube-nocookie\.com)\/embed\/([a-zA-Z0-9_-]+)[^"]*"[^>]*><\/iframe>/is';
+
+        $content = preg_replace_callback($patternStandalone, function ($matches) {
+            $videoId = $matches[1];
+            return $this->renderer->render($videoId);
+        }, $content);
+
+        return $content;
+    }
+}