feat(core): add models for account

src/FiscalOS.Core/Accounts/AccountMetadata.cs

@@ -0,0 +1,15 @@
+namespace FiscalOS.Core.Accounts;
+
+public abstract class AccountMetadata : Entity
+{
+  private readonly string _type;
+
+  public string Type => _type;
+
+  public Guid AccountId { get; init; }
+
+  protected AccountMetadata(string type)
+  {
+    _type = type;
+  }
+}