Added backups of all data, restorable on another computer (#1008)

Co-authored-by: Thorsten Sommer <SommerEngineering@users.noreply.github.com>

app/MindWork AI Studio/Tools/ChatArchive/ChatArchiveManifest.cs

@@ -0,0 +1,32 @@
+namespace AIStudio.Tools.ChatArchive;
+
+/// <summary>
+/// The chats a backup holds, so that the user sees them before any is added.
+/// </summary>
+public sealed record ChatArchiveManifest
+{
+    /// <summary>
+    /// When the backup was made.
+    /// </summary>
+    public DateTimeOffset CreatedAt { get; init; }
+
+    /// <summary>
+    /// The AI Studio version which made the backup. Informational only.
+    /// </summary>
+    public string AppVersion { get; init; } = string.Empty;
+
+    /// <summary>
+    /// All workspaces with chats in the backup.
+    /// </summary>
+    public List<ChatArchiveManifestWorkspace> Workspaces { get; init; } = [];
+
+    /// <summary>
+    /// All temporary chats in the backup.
+    /// </summary>
+    public List<ChatArchiveManifestChat> TemporaryChats { get; init; } = [];
+
+    /// <summary>
+    /// Gets the total number of chats in the backup.
+    /// </summary>
+    public int TotalChatCount => this.Workspaces.Sum(workspace => workspace.Chats.Count) + this.TemporaryChats.Count;
+}