feat: Add booking control during events

- Add allow_booking_during_event boolean field to events (defaults to false)
- Implement booking_allowed? method to check if tickets can be purchased
- Add event_started? and event_ended? helper methods
- Include new option in event edit form with clear explanation
- Display booking policy status on event show page
- Add visual indicator when booking is disabled during ongoing events
- Update controller to permit new parameter

This allows promoters to control whether attendees can purchase tickets
after an event has started, providing flexibility for different event types.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/views/promoter/events/show.html.erb

@@ -144,6 +144,18 @@
         </div>
       </div>
     <% end %>
+
+    <% if @event.published? && @event.event_started? && !@event.allow_booking_during_event? %>
+      <div class="bg-orange-50 border border-orange-200 rounded-2xl p-4 mt-4">
+        <div class="flex items-center">
+          <i data-lucide="clock" class="w-5 h-5 text-orange-400 mr-3"></i>
+          <div>
+            <h3 class="text-sm font-medium text-orange-900">Réservations fermées</h3>
+            <p class="text-sm text-orange-700">L'événement a commencé et les nouvelles réservations sont désactivées.</p>
+          </div>
+        </div>
+      </div>
+    <% end %>
   </div>
 
   <!-- Event details -->
@@ -219,6 +231,18 @@
             <span class="text-sm text-gray-500">Modifié le</span>
             <p class="text-sm"><%= @event.updated_at.strftime("%d/%m/%Y à %H:%M") %></p>
           </div>
+          <div>
+            <span class="text-sm text-gray-500">Réservation pendant l'événement</span>
+            <p class="text-sm flex items-center">
+              <% if @event.allow_booking_during_event? %>
+                <i data-lucide="check-circle" class="w-4 h-4 text-green-500 mr-1"></i>
+                Autorisée
+              <% else %>
+                <i data-lucide="x-circle" class="w-4 h-4 text-red-500 mr-1"></i>
+                Interdite
+              <% end %>
+            </p>
+          </div>
           <% if @event.start_time %>
             <div>
               <span class="text-sm text-gray-500">Début</span>