fix(website): update hero video asset and changelog notes

Replace `public/zblade.mp4` with refreshed demo video
Center and constrain hero video container on the homepage
Update changelog with TTFT improvement and chat image resend bug fix

src/pages/changelog.astro

@@ -41,7 +41,7 @@ import BaseLayout from '../layouts/BaseLayout.astro';
                 Enhancements
               </h3>
               <ul class="changes-list">
-                <li><strong>Zaguán Coder Daemon.</strong> Tightened up the logic for Google Gemini 3.1 Pro.</li>
+                <li><strong>Zaguán Coder Daemon.</strong> Tightened up the logic for Google Gemini 3.1 Pro. TTFT now 4-5x faster.</li>
                 <li><strong>Git Panel.</strong> Enhanced Git Panel to show a strikethrough for elements that are moved, renamed or deleted.</li>
                 <li><strong>Chat.</strong> Added visual feedback while waiting for the model to respond in the chat.</li>
               </ul>
@@ -58,6 +58,7 @@ import BaseLayout from '../layouts/BaseLayout.astro';
                 <li><strong>Paste image.</strong> Fixed a bug where pasting images from clipboard into chat didn't work.</li>
                 <li><strong>Tab focus.</strong> Active tab now always stays in focus while new tabs are opening.</li>
                 <li><strong>Git.</strong> Fixed a bug where the <code>.zblade</code> directory would be submitted to git.</li>
+                <li><strong>Chat.</strong> Fixed a bug where images attached to a message were being re-sent on every subsequent turn, causing context bloat.</li>
               </ul>
             </div>
           </div>