feat: make exams on the calendar sortable

lib/exmr_web/live/exam_live/index.html.heex

@@ -111,7 +111,11 @@
         <%= if Map.has_key?(@events, date) do %>
           <ul class="text-xs">
             <%= for event <- @events[date] do %>
-              <li id={"event-#{event.id}"}>{event.subject}</li>
+              <li id={"event-#{event.id}"}>
+                <button phx-click="edit" phx-value-id={event.id}>
+                  {event.subject}
+                </button>
+              </li>
             <% end %>
           </ul>
         <% end %>