fix: address review on the notification pushes

- Force-join's RoomUpdate carries the room's role grants, so it no
  longer wipes them from the client's cached room.
- The consumable push reports IsTransferable the same as the inventory
  list does.
- A rejected private-instance join sends the owner at most one "wants
  to join" message per requester and instance every 5 minutes.
- SubscribeToPlayers ignores sets over 5,000 ids and keeps the current
  subscriptions.
- The subscriber exclusion list looks up online friends' connections in
  one pipelined Redis batch instead of one call per friend.

DorkNet.Server/Controllers/API/Inventory/InventoryController.cs

@@ -463,7 +463,9 @@ public class InventoryController(
         CreatedAt = inv.AcquiredAt,
         ActiveDurationMinutes = (int?)null,
         inv.IsActive,
-        IsTransferable = true,
+        // Same as GET api/consumables/v2/getUnlocked, so a push never flips
+        // what the inventory list says.
+        IsTransferable = false,
     };
 
     private static object ToConsumableWire(PlayerInventoryEntity inv, StoreItemEntity item)