Add mail categories support

Wino.Core.Domain/Entities/Mail/MailCategory.cs

@@ -0,0 +1,25 @@
+using System;
+using SQLite;
+using Wino.Core.Domain.Enums;
+
+namespace Wino.Core.Domain.Entities.Mail;
+
+public class MailCategory
+{
+    [PrimaryKey]
+    public Guid Id { get; set; }
+
+    public Guid MailAccountId { get; set; }
+
+    public string RemoteId { get; set; }
+
+    public string Name { get; set; }
+
+    public bool IsFavorite { get; set; }
+
+    public string BackgroundColorHex { get; set; }
+
+    public string TextColorHex { get; set; }
+
+    public MailCategorySource Source { get; set; } = MailCategorySource.Local;
+}

Wino.Core.Domain/Entities/Mail/MailCategoryAssignment.cs

@@ -0,0 +1,14 @@
+using System;
+using SQLite;
+
+namespace Wino.Core.Domain.Entities.Mail;
+
+public class MailCategoryAssignment
+{
+    [PrimaryKey]
+    public Guid Id { get; set; }
+
+    public Guid MailCategoryId { get; set; }
+
+    public Guid MailCopyUniqueId { get; set; }
+}

Wino.Core.Domain/Entities/Shared/MailAccount.cs

@@ -132,5 +132,10 @@ public class MailAccount
     /// </summary>
     public bool IsAliasSyncSupported => ProviderType == MailProviderType.Gmail || ProviderType == MailProviderType.Outlook;
 
+    /// <summary>
+    /// Gets whether the account can perform category definition sync type.
+    /// </summary>
+    public bool IsCategorySyncSupported => ProviderType == MailProviderType.Outlook;
+
     public override string ToString() => Name;
 }