feat: show learning progress in web app

internal/webapp/static/index.html

@@ -61,6 +61,16 @@
         <div id="feedback" class="feedback empty-state">
           Submit an answer to see grade, evidence, and follow-up.
         </div>
+        <div class="section-heading progress-heading">
+          <div>
+            <p class="eyebrow">Progress</p>
+            <h2>Learning state</h2>
+          </div>
+          <button id="refresh-progress" class="small-button" type="button" disabled>Refresh</button>
+        </div>
+        <div id="progress" class="feedback empty-state">
+          Answer once to update learner memory and readiness.
+        </div>
       </aside>
     </main>
     <script src="/assets/app.js" type="module"></script>