feat: create follow-up work from updates (Closes #663)

frontend/index.html

@@ -683,6 +683,7 @@
       </div>
       <button class="share-work-route" type="button">Share</button>
       <button id="acknowledge-update-next" type="button" hidden aria-label="Acknowledge and open next update">👍 Acknowledge &amp; next</button>
+      <button id="create-update-follow-up" type="button" hidden>Create follow-up</button>
       <button id="mark-update-read-next" type="button">Mark read &amp; next</button>
       <a id="open-update-gitea" href="#" target="_blank" rel="noopener noreferrer">Open in Gitea</a>
       <details class="detail-defer"><summary>Defer</summary><div class="detail-defer-options"><button type="button" data-detail-defer-preset="today" disabled data-planning-disabled>Later today</button><button type="button" data-detail-defer-preset="tomorrow" disabled data-planning-disabled>Tomorrow</button><button type="button" data-detail-defer-custom disabled data-planning-disabled>Choose date &amp; time</button><button type="button" data-detail-defer-cancel>Cancel</button></div></details>
@@ -930,6 +931,7 @@
 <script src="static/today-sync.js"></script>
 <script src="static/today-rollover.js"></script>
 <script src="static/update-ownership.js"></script>
+<script src="static/update-follow-up.js"></script>
 <script src="static/later-work.js"></script>
 <script src="static/later-sync.js"></script>
 <script src="static/later-and-start.js"></script>