workout: add core finisher to Day C card

workout/2026-04-10.html

@@ -112,6 +112,39 @@
       <div class="note"><strong>Structure:</strong> 3 rounds, 60–90s rest between rounds</div>
     </div>
 
+    <div class="section">
+      <h2>Core Finisher</h2>
+      <div class="table">
+        <table>
+          <thead><tr><th>#</th><th>Exercise</th><th>Reps</th><th>Weight</th><th>Notes</th></tr></thead>
+          <tbody>
+            <tr>
+              <td>1</td>
+              <td class="exercise-name">Dead Bugs</td>
+              <td class="reps">10/side</td>
+              <td class="weight">Bodyweight</td>
+              <td class="form-note">Back flat, extend opposite arm+leg slowly</td>
+            </tr>
+            <tr>
+              <td>2</td>
+              <td class="exercise-name">Russian Twists</td>
+              <td class="reps">20 total</td>
+              <td class="weight">8 lb KB or 10 lb DB</td>
+              <td><a href="https://www.youtube.com/watch?v=wkD8rjkodUI" class="video-link">▶ Video</a></td>
+            </tr>
+            <tr>
+              <td>3</td>
+              <td class="exercise-name">Plank Hold</td>
+              <td class="reps">30-45s</td>
+              <td class="weight">Bodyweight</td>
+              <td><a href="https://www.youtube.com/watch?v=ASdvN_XEl_c" class="video-link">▶ Video</a></td>
+            </tr>
+          </tbody>
+        </table>
+      </div>
+      <div class="note"><strong>2 rounds,</strong> minimal rest. No rest between exercises — move straight through.</div>
+    </div>
+
     <a href="index.html" class="back-link">← Back to workout list</a>
   </div>