fix: add bun as runtime option

Author: steipete

src/pages/index.astro

@@ -106,7 +106,7 @@ import Layout from '../layouts/Layout.astro';
 <span class="code-prompt">$</span> bun run clawdbot onboard</code></pre>
       </div>
       <p class="quickstart-note">
-        Works on macOS, Windows & Linux. Node ≥22 required.
+        Works on macOS, Windows & Linux. Node ≥22 or bun required.
       </p>
     </section>