Created API Controllers (#1)

Removed strongly typed inventory objects

Added EAV inventory types

Added EAV object handling philosophy

Added controllers

Added EF Core migration integration

Reviewed-on: #1

WyvernInventory.Core/Models/InventoryItem.cs

@@ -0,0 +1,10 @@
+namespace WyvernInventory.Core.Models;
+
+public record InventoryItem
+{
+    public int? Id { get; set; }
+    public string? Name { get; set; } = "";
+    public int? TypeId { get; set; }
+    public InventoryType? Type { get; set; } = null!;
+    public List<InventoryAttributeValue>? AttributeValues { get; set; } = [];
+}