Standardize: Convert 7 high-priority $conn->query() to prepared statements

Converted queries in:
- functions.php:
  * getTripCount() - Hardcoded query
  * getAvailableSpaces() - Two queries using $trip_id parameter (HIGH PRIORITY)

- blog.php:
  * Main blog list query - Hardcoded 'published' status

- course_details.php:
  * Driver training courses query - Hardcoded course type

- driver_training.php:
  * Future driver training dates query - Hardcoded course type

- events.php:
  * Upcoming events query - Hardcoded date comparison

- index.php:
  * Featured trips query - Hardcoded published status

All queries now use proper parameter binding via prepared statements.
Next: Convert remaining 15+ safe hardcoded queries for consistency.

blog.php

@@ -28,10 +28,10 @@ include_once('header.php') ?>
 
 
     }
-</style><?php
-    $pageTitle = 'Blogs';
-    $breadcrumbs = [['Home' => 'index.php']];
-    require_once('components/banner.php');
+</style><?php
+    $pageTitle = 'Blogs';
+    $breadcrumbs = [['Home' => 'index.php']];
+    require_once('components/banner.php');
 ?>
 
 
@@ -41,9 +41,11 @@ include_once('header.php') ?>
         <div class="row">
             <div class="col-lg-8">
                 <?php
-                // Query to retrieve data from the trips table
-                $sql = "SELECT blog_id, title, date, category, image, description, author, members_only, link FROM blogs WHERE status = 'published' ORDER BY date DESC";
-                $result = $conn->query($sql);
+                // Query to retrieve data from blogs table
+                $stmt = $conn->prepare("SELECT blog_id, title, date, category, image, description, author, members_only, link FROM blogs WHERE status = ? ORDER BY date DESC");
+                $stmt->bind_param("s", $status = 'published');
+                $stmt->execute();
+                $result = $stmt->get_result();
 
                 if ($result->num_rows > 0) {
                     // Loop through each row