Added mailboxes as local data sources (#1022)

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

@@ -0,0 +1,21 @@
+namespace AIStudio.Tools.Databases.IndexStore;
+
+/// <summary>
+/// A sign-in the server refused. While the row exists, AI Studio does not try to sign in again.
+/// </summary>
+/// <remarks>
+/// The row has no foreign key on purpose. Rebuilding the index deletes the data source row and
+/// everything which cascades from it, and a refused sign-in has to survive that: otherwise every
+/// rebuild would try the refused password again, which is how a directory account gets locked.
+/// </remarks>
+internal sealed class MailboxAuthStateEntity
+{
+    public string DataSourceId { get; set; } = string.Empty;
+
+    public DateTimeOffset FailedAtUtc { get; set; }
+
+    /// <summary>
+    /// What the server answered, empty when it gave no reason.
+    /// </summary>
+    public string FailureMessage { get; set; } = string.Empty;
+}