merged gc rework branch, but deleted all migrations as they're incompatible

src/EllieBot/Db/Models/xp/ExcludedItem.cs

@@ -0,0 +1,13 @@
+namespace EllieBot.Db.Models;
+
+public class ExcludedItem : DbEntity
+{
+    public ulong ItemId { get; set; }
+    public ExcludedItemType ItemType { get; set; }
+
+    public override int GetHashCode()
+        => ItemId.GetHashCode() ^ ItemType.GetHashCode();
+
+    public override bool Equals(object? obj)
+        => obj is ExcludedItem ei && ei.ItemId == ItemId && ei.ItemType == ItemType;
+}