feat: add native code block feature and optimize asset loading

- Implemented custom code block system with Prism.js highlighting (YAML)
- Added Gutenberg block with modal editor for better handling of large code snippets
- Added Classic Editor button with dialog for structured code input
- Implemented copy-to-clipboard functionality with hover-based UI
- Introduced dedicated styling (code.css)

Performance improvements:
- Load Prism.js and code block assets only when a code block is present
- Reduced unnecessary JS and CSS on pages without code snippets
- Improved overall frontend performance and resource efficiency

UI/UX improvements:
- Adapted code block styling to match theme design (rectangular layout, accent border, integrated color scheme)
- Refactored sidebar search styling for consistent appearance
- Removed conflicting wrapper borders causing double border rendering
- Applied single-border input pattern with clean focus state
- Fixed invalid CSS !important syntax issues
- Aligned search input design with comments and code block components

Result:
- Cleaner UI with consistent component styling
- Improved performance through conditional asset loading
- Better authoring experience for structured YAML content

inc/tools/code-block.php

@@ -16,6 +16,34 @@ if ( ! defined( 'ABSPATH' ) ) {
 	exit;
 }
 
+/**
+ * Check if current post content contains code blocks.
+ *
+ * @return bool
+ */
+function ztfr_has_code_block() {
+
+	if ( is_admin() ) {
+		return false;
+	}
+
+	if ( ! is_singular() ) {
+		return false;
+	}
+
+	global $post;
+
+	if ( ! isset( $post ) || empty( $post->post_content ) ) {
+		return false;
+	}
+
+	if ( has_block( 'ztfr/code-block', $post ) ) {
+		return true;
+	}
+
+	return false !== strpos( $post->post_content, '<pre' );
+}
+
 /**
  * Get asset version from file modification time.
  *
@@ -40,6 +68,10 @@ function ztfr_enqueue_code_assets() {
 	if ( is_admin() ) {
 		return;
 	}
+	
+	if ( ! ztfr_has_code_block() ) {
+		return;
+	}
 
 	$code_css_version = ztfr_code_asset_version( '/assets/css/code.css' );
 	$prism_version    = ztfr_code_asset_version( '/assets/js/prism.js' );