Add new templates and tests for improved functionality

- Created index.html template for the homepage with service cards and partner logos.
- Added page_from_md.html template for rendering pages from markdown.
- Developed services.html template detailing various services offered.
- Implemented tests for link handling in markdown, ensuring external links open in new tabs and internal links function correctly.
- Enhanced markdown parser tests to validate heading extraction, content rendering, and link safety.
- Introduced utility tests for template rendering, HTML minification, and JavaScript minification.

Co-authored-by: Copilot <copilot@github.com>

templates/_footer.html

@@ -0,0 +1,9 @@
+<div id="footer">
+  <div class="container">
+    <p>
+      &copy; 2025
+      <a href="imprint.html" class="footer-link">AllYouCanGET</a>
+      &nbsp;|&nbsp; All rights reserved.
+    </p>
+  </div>
+</div>