Announcement for Blender Projects changing its Git SSH domain (#15)

I've added an announcement using Gitea styling:
- Date of switchover (still needs to be determined)
- Commands to update Git Remote
- Link to DevTalk announcement post
- JavaScript to be able to dismiss the banner indefinitely (using Key-Value saved in browser LocalStorage)

Reviewed-on: https://projects.blender.org/infrastructure/gitea-custom/pulls/15

templates/custom/body_inner_pre.tmpl

@@ -562,7 +562,7 @@
 
       <ul class="nav-global-nav-links nav-global-dropdown" id="nav-global-nav-links">
         <li>
-          <a href="https://projects.blender.org" class="is-active">Projects</a>
+          <a href="/" class="is-active">Projects</a>
         </li>
         <li>
           <a href="https://developer.blender.org/docs/">Docs</a>
@@ -726,6 +726,48 @@
   </div>
 </div>
 
+<div id="blender-ssh-announcement" class="ui tab active list" style="max-width: 800px; margin: 1rem auto; padding: 1rem;">
+  <h4 class="ui top attached header tw-flex tw-items-center">
+    <div class="tw-flex-1 tw-flex tw-items-center">
+      Blender Projects is moving to a new Git SSH domain!
+    </div>
+    <a href="#" id="blender-ssh-announcement-close" class="tw-flex tw-items-center muted"
+      data-tooltip-content="Don't show this again" aria-label="Don't show this again">
+      {{svg "octicon-x"}}
+    </a>
+  </h4>
+
+  <div class="ui attached segment">
+    <p>To avoid issues, update the Git remote of your repositories before <strong>July 1, 2025</strong>:<br></p>
+    <code class="chroma language-sh display">git remote set-url &lt;remote&gt; git@git.blender.org:&lt;user<span class="p">|</span>org&gt;/&lt;repo&gt;.git</code>
+    <p><br>Replace <em>&lt;remote&gt;</em>, <em>&lt;user|org&gt;</em>, and <em>&lt;repo&gt;</em> with your actual values.<br></p>
+    <a href="https://devtalk.blender.org/t/blender-projects-is-moving-its-git-ssh-domain-to-git-blender-org/41098" target="_blank" rel="noopener">
+      <button class="ui primary button">Read more on DevTalk</button>
+    </a>
+  </div>
+</div>
+
+<script>
+  (function () {
+    const storageKey = 'blenderAnnouncementDismissed';
+    const announcement = document.getElementById('blender-ssh-announcement');
+    const closeBtn = document.getElementById('blender-ssh-announcement-close');
+
+    // If dismissed previously, hide the announcement
+    if (localStorage.getItem(storageKey) === 'true') {
+      announcement.style.display = 'none';
+      return;
+    }
+
+    // Dismiss on click and store in localStorage
+    closeBtn.addEventListener('click', function (e) {
+      e.preventDefault(); // Prevent href="#" jump
+      announcement.style.display = 'none';
+      localStorage.setItem(storageKey, 'true');
+    });
+  })();
+</script>
+
 <style>
   /* Custom styling for projects.blender.org */
   /* Make sure to start every line with ".nav-global"