build: add -ldl linker flag, recursive source discovery, and API test targets to Makefile

tests/project_root/js/main.js

@@ -0,0 +1,9 @@
+// Main JavaScript file for future enhancements
+
+// Example: Smooth scroll for navigation links
+document.querySelectorAll('nav a').forEach(link => {
+    link.addEventListener('click', function(e) {
+        e.preventDefault();
+        document.querySelector(this.getAttribute('href')).scrollIntoView({ behavior: 'smooth' });
+    });
+});