fix(activity): revert to synthetic schedule - real ids black-screen the events page

The events page NREs when the schedule references real activities: the
client renders their panels and requests per-activity data
(GetActivityHotData/GetActiveActivityData/...) that this PS cannot fill
yet, Sync(nil) -> black screen. The synthetic list resolves to nothing
and keeps the page open (empty but usable).

realActivitySchedule stays in handlers_activity_data.go for the future
round where per-activity data handlers exist.

internal/gameserver/handlers_challenge.go

@@ -293,12 +293,13 @@ func init() {
 				EndTime:    1924992000,
 			})
 		}
-		// real activity ids from the 4.6.51 client (March7th ActivityConfig
-		// dump) - synthetic ids the client doesn't know just fill the Travel
-		// Log with blank entries
-		for _, e := range realActivitySchedule {
-			add(e.activityID, e.panelID)
-		}
+		// NOTE: the real 4.6.51 activity schedule (realActivitySchedule, from
+		// the March7th dump) BLACK-SCREENS the events page: the client renders
+		// real event panels, then requests each activity's data (GetActivity-
+		// HotData/GetActiveActivityData/...) which we cannot fill yet - NRE.
+		// The synthetic list below resolves to nothing and keeps the page open
+		// (empty but usable). Re-enable the real list only after implementing
+		// per-activity data handlers.
 
 		// Apocalyptic Shadow tab requires an active schedule with panel 21001
 		for actID := uint32(21001); actID <= 21030; actID++ {