feat: protect offline work from storage eviction (Closes #1110)

frontend/index.html

@@ -112,6 +112,10 @@
         <div><strong>Keep work available offline</strong><p class="small" id="device-setup-offline-status" role="status"></p></div>
         <button class="device-setup-action" id="device-setup-offline" type="button">Enable</button>
       </li>
+      <li class="device-setup-step">
+        <div><strong>Protect offline work</strong><p class="small" id="device-setup-protection-status" role="status"></p></div>
+        <button class="device-setup-action" id="device-setup-protection" type="button">Protect</button>
+      </li>
       <li class="device-setup-step">
         <div><strong>Notify me about new updates</strong><p class="small" id="device-setup-push-status" role="status"></p></div>
         <button class="device-setup-action" id="device-setup-push" type="button">Enable</button>