Added mailboxes as local data sources (#1022)

app/MindWork AI Studio/Tools/Databases/IndexStore/MailLocationEntity.cs

@@ -0,0 +1,33 @@
+namespace AIStudio.Tools.Databases.IndexStore;
+
+/// <summary>
+/// One place on the server where a mail lies.
+/// </summary>
+/// <remarks>
+/// A mail can lie in more than one folder, and moving it changes only its locations, never its
+/// embedding. The flags are kept here, not with the mail, because IMAP keeps them per folder: a
+/// copy in another folder has flags of its own.
+/// </remarks>
+internal sealed class MailLocationEntity
+{
+    public int Id { get; set; }
+
+    public string ParentFileId { get; set; } = string.Empty;
+
+    public int FolderId { get; set; }
+
+    /// <summary>
+    /// The UID of the mail within its folder, valid for the UIDVALIDITY of that folder.
+    /// </summary>
+    public long Uid { get; set; }
+
+    public bool IsSeen { get; set; }
+
+    public bool IsFlagged { get; set; }
+
+    public bool IsAnswered { get; set; }
+
+    public MailMessageEntity? Message { get; set; }
+
+    public MailFolderEntity? Folder { get; set; }
+}