docs: add stale localhost ui troubleshooting

backend/workflows/templates/workflows/developer_handbook.html

@@ -624,6 +624,20 @@ make backup-verify BACKUP_DIR=backups/backup_YYYYmmdd_HHMMSS</code></pre>
     </div>
 
     <h2 id="troubleshooting">20) Troubleshooting</h2>
+    <div class="box">
+      <h3>Localhost still looks stale after the server is already fixed</h3>
+      <ol>
+        <li>Hard refresh the page with <code>Cmd + Shift + R</code>.</li>
+        <li>If it still looks wrong, clear site data for <code>127.0.0.1:8088</code> in the browser devtools and sign in again.</li>
+        <li>Restart the local web container:
+          <pre><code>docker compose restart web</code></pre>
+        </li>
+        <li>If the issue still survives, rebuild the local stack:
+          <pre><code>docker compose up -d --build</code></pre>
+        </li>
+      </ol>
+      <p>This is the right order when shared header fixes, page-local CSS fixes, or versioned static assets look correct on the server but localhost still shows the old UI.</p>
+    </div>
     <ul>
       <li><strong>Page looks stale:</strong> restart <code>web</code> and hard-refresh browser</li>
       <li><strong>Second request hangs:</strong> inspect web logs and verify health endpoint</li>