Update template structure and improve accessibility in page.php

The structure of the 'page.php' template of WP Kit Elementor theme has been updated to improve semantics and accessibility. The changes include:
- Addition of a check to exit if the file is accessed directly for improved security.
- Use of 'div' instead of 'main' as main content wrapper, improving HTML semantics for better representation.
- A shift in the sequence of template parts being called for a more logical layout rendering.
These modifications aim to enhance the overall user experience and adherence to best practices in web development.

page.php

@@ -1,14 +1,25 @@
 <?php
 /**
  * The template for displaying all single posts
+ *
+ * @package WPKitElementor
  */
 
-get_header();
-
-while ( have_posts() ) {
-	the_post();
-	get_template_part( 'template-parts/header/page-header' );
-	get_template_part( 'template-parts/content/content-page' );
+if ( ! defined( 'ABSPATH' ) ) {
+	exit; // Exit if accessed directly.
 }
 
-get_footer();
+get_header();
+?>
+<div id="primary" class="content-area">
+	<main id="main" class="site-main">
+		<?php
+		while ( have_posts() ) {
+			the_post();
+			get_template_part( 'template-parts/header/page-header' );
+			get_template_part( 'template-parts/content/content-page' );
+		}
+		?>
+	</main><!-- #main -->
+</div><!-- #primary -->
+<?php get_footer(); ?>