feat: Set up Eleventy and restructure project

Install and configure Eleventy for static site generation.

- Reorganized project directories for Eleventy conventions.
- Created base.njk, header.html, and footer.html for modularity.
- Wrote the initial landing page content in index.njk.

src/includes/footer.html

@@ -0,0 +1,17 @@
+<footer>
+            
+    <ul class="footer-links">
+        <li><a href="#home">Back to Top</a></li>
+        <li><a href="#about">About</a></li>
+        <li><a href="#portfolio">Portfolio</a></li>
+        <li><a href="#contact">Contact</a></li>
+    </ul>
+
+    <ul class="external-links">
+        <li><a href="https://linkedin.com/in/dereklseitz" target="_blank">Connect on LinkedIn</a></li>
+        <li><a href="https://git.dsnet.pro/dereklseitz" target="_blank">My Project Repos</a></li>
+    </ul>
+    
+    <p>&copy; 2025, Derek L.Seitz</p>
+    
+</footer>