Added the visual briefing assistant (#893)

app/MindWork AI Studio/Tools/Media/MediaImportOwnerKind.cs

@@ -5,4 +5,17 @@ public enum MediaImportOwnerKind
 {
     CHAT,
     ASSISTANT,
+
+    /// <summary>
+    /// Identifies persistent media transcripts owned by a visual briefing.
+    /// </summary>
+    /// <remarks>
+    /// A visual briefing cannot use <see cref="ASSISTANT"/>: that kind is keyed by an assistant
+    /// session, which ends when the user navigates away or closes the app. A briefing is a stored
+    /// document that outlives both, and its transcripts are stored next to it. The owner is
+    /// therefore keyed by the briefing ID, see <see cref="MediaImportOwner.ForVisualBriefing"/>.
+    /// This is what lets AI Studio re-associate transcripts with the right briefing after a
+    /// restart, and what lets the UI show a running import on the briefing it belongs to.
+    /// </remarks>
+    VISUAL_BRIEFING,
 }