Further work on static side

PkmnLib.Static/Libraries/ItemLibrary.cs

@@ -0,0 +1,33 @@
+using System.Diagnostics.CodeAnalysis;
+using PkmnLib.Static.Utils;
+
+namespace PkmnLib.Static.Libraries;
+
+/// <summary>
+/// The library for all items in the game.
+/// </summary>
+public interface IReadOnlyItemLibrary
+{
+    /// <summary>
+    /// Tries to get an item from the library. Returns false if the item is not found.
+    /// </summary>
+    bool TryGet(StringKey key, [MaybeNullWhen(false)] out IItem value);
+
+    /// <summary>
+    /// Gets a random item from the library.
+    /// </summary>
+    IItem GetRandom(IRandom random);
+
+    /// <summary>
+    /// The amount of items in the library.
+    /// </summary>
+    int Count { get; }
+
+    /// <summary>
+    /// Whether the library is empty.
+    /// </summary>
+    bool IsEmpty { get; }
+}
+
+/// <inheritdoc cref="IReadOnlyItemLibrary"/>
+public class ItemLibrary : DataLibrary<IItem>, IReadOnlyItemLibrary;