feat(matching): add schedule config for division collision groups

Allow event organizers to configure which divisions run in parallel
(same time slot) for accurate collision detection in the auto-matching
algorithm. Divisions in the same slot will collide with each other.

- Add scheduleConfig JSON field to Event model
- Add PUT /events/:slug/schedule-config API endpoint
- Update matching algorithm to use slot-based collision detection
- Add UI in EventDetailsPage for managing division slots
- Add unit tests for schedule-based collision detection

frontend/src/services/api.js

@@ -430,6 +430,15 @@ export const matchingAPI = {
     });
     return data.data;
   },
+
+  // Set schedule config (admin)
+  async setScheduleConfig(slug, scheduleConfig) {
+    const data = await fetchAPI(`/events/${slug}/schedule-config`, {
+      method: 'PUT',
+      body: JSON.stringify({ scheduleConfig }),
+    });
+    return data.data;
+  },
 };
 
 export { ApiError };