fix(data): harden portfolio publication concurrency

src/GmRelay.Shared/Features/Sessions/ListSessions/DeleteSessionHandler.cs

@@ -62,7 +62,21 @@ public sealed class DeleteSessionHandler(
             return new DeleteSessionResult(false, "Только owner или co-GM может удалять сессию.", null, null, null, false, 0);
         }
 
-        // 2. Delete session
+        // 2. Unpublish a linked portfolio card before its required session link cascades away.
+        await connection.ExecuteAsync(
+            """
+            UPDATE portfolio_games pg
+            SET is_public = false,
+                updated_at = now()
+            FROM portfolio_game_sessions pgs
+            WHERE pgs.portfolio_game_id = pg.id
+              AND pgs.session_id = @SessionId
+              AND pg.is_public = true
+            """,
+            new { command.SessionId },
+            transaction);
+
+        // 3. Delete session
         await connection.ExecuteAsync("DELETE FROM sessions WHERE id = @Id", new { Id = command.SessionId }, transaction);
 
         var remainingInTopic = session.ThreadId.HasValue