Agregar estructura completa del tema APUS con Bootstrap 5 y optimizaciones de rendimiento

Se implementa tema WordPress personalizado para Análisis de Precios Unitarios con funcionalidades avanzadas:
- Sistema de templates (front-page, single, archive, page, 404, search)
- Integración de Bootstrap 5.3.8 con estructura modular de assets
- Panel de opciones del tema con Customizer API
- Optimizaciones de rendimiento (Critical CSS, Image Optimization, Performance)
- Funcionalidades SEO y compatibilidad con Rank Math
- Sistema de posts relacionados y tabla de contenidos
- Badge de categorías y manejo de AdSense diferido
- Tipografías Google Fonts configurables
- Documentación completa del tema y guías de uso

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

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

wp-content/themes/apus-theme/template-parts/content-none.php

@@ -0,0 +1,56 @@
+<?php
+/**
+ * Template part for displaying a message that posts cannot be found
+ *
+ * @link https://developer.wordpress.org/themes/basics/template-hierarchy/
+ *
+ * @package Apus_Theme
+ * @since 1.0.0
+ */
+?>
+
+<section class="no-results not-found">
+
+	<header class="page-header">
+		<h1 class="page-title"><?php esc_html_e( 'Nothing Found', 'apus-theme' ); ?></h1>
+	</header><!-- .page-header -->
+
+	<div class="page-content">
+		<?php
+		if ( is_home() && current_user_can( 'publish_posts' ) ) :
+
+			// Message for users who can publish posts
+			printf(
+				'<p>' . wp_kses(
+					/* translators: 1: link to WP admin new post page. */
+					__( 'Ready to publish your first post? <a href="%1$s">Get started here</a>.', 'apus-theme' ),
+					array(
+						'a' => array(
+							'href' => array(),
+						),
+					)
+				) . '</p>',
+				esc_url( admin_url( 'post-new.php' ) )
+			);
+
+		elseif ( is_search() ) :
+			?>
+
+			<!-- Search returned no results -->
+			<p><?php esc_html_e( 'Sorry, but nothing matched your search terms. Please try again with some different keywords.', 'apus-theme' ); ?></p>
+			<?php
+			get_search_form();
+
+		else :
+			?>
+
+			<!-- Generic no content message -->
+			<p><?php esc_html_e( 'It seems we can&rsquo;t find what you&rsquo;re looking for. Perhaps searching can help.', 'apus-theme' ); ?></p>
+			<?php
+			get_search_form();
+
+		endif;
+		?>
+	</div><!-- .page-content -->
+
+</section><!-- .no-results -->