Added mailboxes as local data sources (#1022)

app/MindWork AI Studio/Tools/Mail/MailboxConnectionFailure.cs

@@ -0,0 +1,37 @@
+namespace AIStudio.Tools.Mail;
+
+/// <summary>
+/// Why a connection to the IMAP server of a mailbox failed.
+/// </summary>
+public enum MailboxConnectionFailure
+{
+    /// <summary>
+    /// The server rejected the username or the password. AI Studio does not try again on its own, because every rejected attempt brings the account closer to being locked.
+    /// </summary>
+    AUTHENTICATION_FAILED,
+
+    /// <summary>
+    /// The server could not be reached or stopped answering, e.g., without a VPN connection. Says nothing about the password.
+    /// </summary>
+    NETWORK_UNAVAILABLE,
+
+    /// <summary>
+    /// No encrypted connection came about: the certificate of the server was not trusted, or the server does not offer STARTTLS.
+    /// </summary>
+    TLS_FAILED,
+
+    /// <summary>
+    /// The server refused a command, or answered in a way the IMAP client did not understand.
+    /// </summary>
+    SERVER_ERROR,
+
+    /// <summary>
+    /// The settings of the mailbox are incomplete, or this version of AI Studio does not know them. Nothing was sent to the server.
+    /// </summary>
+    INVALID_SETTINGS,
+
+    /// <summary>
+    /// The organization allows only its own mail servers, and the server of the mailbox is none of them. Nothing was sent to the server.
+    /// </summary>
+    SERVER_NOT_ALLOWED,
+}