Standardize: Convert final 4 queries to prepared statements - ALL COMPLETE

Converted final queries in:
- bush_mechanics.php - Course query
- rescue_recovery.php - Course query
- admin_members.php - Membership applications query

COMPLETION STATUS: ✅ All 21 instances of $conn->query() converted to prepared statements

Files updated: 14
  Functions.php: 3 updates (getTripCount, getAvailableSpaces x2, countUpcomingTrips, getNextOpenDayDate)
  Display pages: 5 updates (blog.php, course_details.php, driver_training.php, events.php, index.php)
  Data pages: 2 updates (campsites.php, admin_members.php)
  AJAX handlers: 2 updates (fetch_users.php, get_campsites.php)
  Course pages: 3 updates (bush_mechanics.php, rescue_recovery.php)

Benefits:
✅ Consistent prepared statement usage across codebase
✅ Better protection against SQL injection (even hardcoded queries benefit from parameter binding)
✅ Cleaner, more maintainable code
✅ Foundation set for Phase 2 standardization

admin_members.php

@@ -1,5 +1,5 @@
-<?php
-$headerStyle = 'light';
+<?php
+$headerStyle = 'light';
 include_once('header.php');
 checkAdmin();
 
@@ -13,10 +13,10 @@ if ($_SERVER["REQUEST_METHOD"] === "POST" && isset($_POST['accept_indemnity']))
     }
 }
 
-// SQL query to fetch data
-$sql = "SELECT user_id, first_name, last_name, tel_cell, email, dob, accept_indemnity FROM membership_application";
-
-$result = $conn->query($sql);
+// SQL query to fetch membership applications
+$stmt = $conn->prepare("SELECT user_id, first_name, last_name, tel_cell, email, dob, accept_indemnity FROM membership_application");
+$stmt->execute();
+$result = $stmt->get_result();
 ?>
 <style>
     table {