fix: Complete memory leak fix for shortcode context handling

- Changed shortcode context from boolean to depth counter for nested shortcodes
- Added shortcode context protection to template-wrapper.php for single page views
- Fixes remaining recursion path in single FediStream post views

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

includes/Frontend/template-wrapper.php

@@ -13,6 +13,9 @@ if ( ! defined( 'ABSPATH' ) ) {
 use WP_FediStream\Plugin;
 use WP_FediStream\Frontend\TemplateLoader;
 
+// Enter shortcode context to prevent recursive shortcode processing in post content.
+TemplateLoader::enter_shortcode_context();
+
 // Get template context.
 $context = TemplateLoader::get_context();
 
@@ -75,4 +78,7 @@ get_header();
 </main>
 
 <?php
+// Exit shortcode context.
+TemplateLoader::exit_shortcode_context();
+
 get_footer();