docs(changelog): finalize v0.3.1 release notes

- Set v0.3.1 status to latest with February 23, 2026 release date
- Update v0.3.0 badge from latest to previous
- Add frontend and backend dependency update entry

src/pages/changelog.astro

@@ -25,13 +25,13 @@ import BaseLayout from '../layouts/BaseLayout.astro';
     <!-- v0.3.1 Section -->
     <section class="changelog-section">
       <div class="container">
-        <div class="version-card version-development">
+        <div class="version-card version-latest">
           <div class="version-header">
             <div class="version-info">
               <h2 class="version-number">v0.3.1</h2>
-              <span class="version-date">TBD</span>
+              <span class="version-date">February 23, 2026</span>
             </div>
-            <span class="version-badge badge-development">Development</span>
+            <span class="version-badge badge-latest">Latest</span>
           </div>
           
           <div class="version-content">
@@ -43,6 +43,7 @@ import BaseLayout from '../layouts/BaseLayout.astro';
               <ul class="changes-list">
                 <li><strong>Zaguán Coder Daemon.</strong> Added stronger detection for Google Gemini if it was unable to apply a patch to help it recover and try again instead of hanging.</li>
                 <li><strong>Zaguán Coder Daemon.</strong> Added a runtime guard to prevent AI models from inappropriately using shell commands (e.g., <code>grep</code>, <code>cat</code>) instead of dedicated tools, automatically guiding them to correct usage.</li>
+                <li><strong>Dependencies.</strong> Updated modules for frontend and backend.</li>
               </ul>
             </div>
 
@@ -65,13 +66,13 @@ import BaseLayout from '../layouts/BaseLayout.astro';
     <!-- v0.3.0 Section -->
     <section class="changelog-section">
       <div class="container">
-        <div class="version-card version-latest">
+        <div class="version-card">
           <div class="version-header">
             <div class="version-info">
               <h2 class="version-number">v0.3.0</h2>
               <span class="version-date">February 23, 2026</span>
             </div>
-            <span class="version-badge badge-latest">Latest</span>
+            <span class="version-badge badge-previous">Previous</span>
           </div>
           
           <div class="version-content">