Add interactive Base 4 track map with Leaflet.js

- Created new track-map page with aerial image and SVG overlay
- Implemented custom rotated square markers with obstacle numbers
- Added admin edit mode for placing and repositioning markers
- Database migration for track_obstacles table
- Modal form for adding new obstacles (replaces browser alerts)
- Drag-to-reposition functionality with auto-save
- Color-coded markers (green/red/black/split) for difficulty levels
- Clickable popups showing obstacle details
- Added track-map to navigation menu and sitemap
- URL rewrite rule for clean /track-map URL

index.php

@@ -687,6 +687,10 @@ if (countUpcomingTrips() > 0) { ?>
             <h2>✨ What's New</h2>
         </div>
         <div class="updates-modal-body">
+            <div class="update-item">
+                <h3><i class="fas fa-images" style="margin-right: 10px; color: #e90000;"></i>Track Map</h3>
+                <p>Interactive map of the BASE4 4x4 Training Track.</p>
+            </div>
             <div class="update-item">
                 <h3><i class="fas fa-images" style="margin-right: 10px; color: #e90000;"></i>Photo Gallery</h3>
                 <p>Explore and share memories from club events and trips. Members can now upload and view photos from past adventures.</p>