feat(blog): add blog section and rss feed

- Add blog content collection schema and welcome post
- Create blog index, post layout components, and dynamic routing
- Add `@astrojs/rss` dependency and implement RSS feed generation
- Add blog links to header and footer navigation
- Update changelog with Gemini 3.1 Pro enhancement notes

src/pages/changelog.astro

@@ -41,6 +41,7 @@ import BaseLayout from '../layouts/BaseLayout.astro';
                 Enhancements
               </h3>
               <ul class="changes-list">
+                <li><strong>Google Gemini 3.1 Pro.</strong> Trying to make Google Gemini 3.1. Pro work better based on feedback and other OSS projects.</li>
                 <li><strong>Google Gemini.</strong> Updated our Google Gemini implementation in Zaguán Coder Daemon.</li>
                 <li><strong>MiniMax.</strong> Updated our MiniMax implementation for Fireworks in Zaguán Coder Daemon.</li>
               </ul>