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.

.vscode/settings.json

@@ -0,0 +1,5 @@
+{
+    "cSpell.words": [
+        "wireframing"
+    ]
+}