Add client-side search using Lunr

templates/layout.njk

@@ -16,6 +16,7 @@
     </main>
   </div>
   {% include "partials/footer.njk" %}
+  <script src="/assets/lunr.js"></script>
   <script src="/assets/theme.js"></script>
 </body>
 </html>

templates/partials/header.njk

@@ -1,5 +1,7 @@
 <header class="header">
   <button id="sidebar-toggle" class="sidebar-toggle" aria-label="Toggle navigation">☰</button>
   <a href="/" class="logo">{{ config.site.title }}</a>
+  <input id="search-input" class="search-input" type="search" placeholder="Search..." aria-label="Search" />
   <button id="theme-toggle" class="theme-toggle" aria-label="Toggle dark mode">🌓</button>
+  <div id="search-results" class="search-results"></div>
 </header>