✨feature: Use single file for global navigation, include on other pages

main-menu.php

@@ -0,0 +1,9 @@
+<div class="mb-6">
+    <a href="index.php" class="text-blue-400 hover:underline">Dashboard</a>
+    <span class="mx-2">|</span>
+    <a href="buy-ships.php" class="text-blue-400 hover:underline">Buy Ships</a>
+    <span class="mx-2">|</span>
+    <a href="mining-fleet.php" class="text-blue-400 hover:underline">Mining Fleet</a>
+    <span class="mx-2">|</span>
+    <a href="config.php" class="text-blue-400 hover:underline">Configuration</a>
+</div>