Migrate UI to Lucide icons, reorder sidebar, and polish journal/groups UX

- Replace emoji icons with Lucide across admin pages; add vendor/lucide.min.js and renderIcons() helper\n- Reorder sidebar logically (Dashboard, Journal, Students, Groups, Files, Links, Trash + admin sections)\n- Groups: open photo chronology only via the Фото button; covers no longer clickable\n- Journal: show group badge over card photo, compact AI-status icon beside description, and date range in empty-state message\n- Update README (AI worker, Lucide, worker.js)

public/worker.html

@@ -96,6 +96,7 @@
   </div>
 </div>
 <div class="toast" id="toast"></div>
+<script src="vendor/lucide.min.js"></script>
 <script src="admin.js"></script>
 <script src="js/worker.js"></script>
 </body>