Refactor: Extract header and footer into reusable snippets

- Created site/snippets/header.php with parameterized title and template
- Created site/snippets/footer.php with optional additional scripts
- Updated home.php and product.php to use the new snippets
- Reduces code duplication and improves maintainability

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

site/snippets/footer.php

@@ -0,0 +1,19 @@
+    <footer id="site-footer">
+        <div class="site-footer__container">
+            <div class="footer__mentions">
+                <p class="p__small">
+                    © <?= date('Y') ?> Index Investigation |
+                    <a target="_blank" href="https://www.index.ngo/mentions-legales/">Mentions légales</a>
+                </p>
+            </div>
+        </div>
+    </footer>
+
+    <script src="<?= url('assets/js/onload.js') ?>"></script>
+    <?php if(isset($scripts) && is_array($scripts)): ?>
+        <?php foreach($scripts as $script): ?>
+    <script src="<?= url($script) ?>"></script>
+        <?php endforeach ?>
+    <?php endif ?>
+</body>
+</html>