feat: Add event automation system for plugins attached to appointments

- Add GlobalEventPlugin model for auto-attaching plugins to all events
- Create signals for auto-attachment on new events and rescheduling
- Add API endpoints for global event plugins (CRUD, toggle, reapply)
- Update CreateTaskModal with "Scheduled Task" vs "Event Automation" choice
- Add option to apply to all events or future events only
- Display event automations in Tasks page alongside scheduled tasks
- Add EditEventAutomationModal for editing trigger and timing
- Handle event reschedule - update Celery task timing on time/duration changes
- Add Marketplace to Plugins menu in sidebar

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

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

frontend/src/pages/OwnerScheduler.tsx

@@ -10,6 +10,7 @@ import { useResources } from '../hooks/useResources';
 import { useServices } from '../hooks/useServices';
 import { useAppointmentWebSocket } from '../hooks/useAppointmentWebSocket';
 import Portal from '../components/Portal';
+import EventAutomations from '../components/EventAutomations';
 
 // Time settings
 const START_HOUR = 0;  // Midnight
@@ -1786,6 +1787,13 @@ const OwnerScheduler: React.FC<OwnerSchedulerProps> = ({ user, business }) => {
                   </div>
                 )}
 
+                {/* Automations - only show for saved appointments */}
+                {selectedAppointment.id && (
+                  <div className="p-3 bg-purple-50 dark:bg-purple-900/20 rounded-lg border border-purple-200 dark:border-purple-800">
+                    <EventAutomations eventId={selectedAppointment.id} compact />
+                  </div>
+                )}
+
                 {/* Action Buttons */}
                 <div className="pt-4 flex justify-end gap-3 border-t border-gray-200 dark:border-gray-700">
                   <button