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.

package.json

@@ -0,0 +1,23 @@
+{
+  "name": "dereklseitz.github.io",
+  "version": "1.0.0",
+  "description": "Portfolio website",
+  "main": "script.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/dereklseitz/dereklseitz.github.io.git"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "bugs": {
+    "url": "https://github.com/dereklseitz/dereklseitz.github.io/issues"
+  },
+  "homepage": "https://github.com/dereklseitz/dereklseitz.github.io#readme",
+  "devDependencies": {
+    "@11ty/eleventy": "^3.1.2"
+  }
+}